Global Drought Indices
Monitoring the climate at various timescales allows identification of short-term wet periods within long-term droughts or short-term dry spells within long-term wet periods. Indices can simplify complex relationships and provide useful communication tools for diverse audiences and users, including the public. [ Reference: WMO Handbook on Indicators and Indices ]
Global Drought Indicators and Indices
Drought.gov, and numerous partners, create drought indices from various indicators to compare current conditions to historical averages and simplify the results on a standard scale of drought intensity categories of D0 through D4.
Indicators are variables or parameters used to describe drought conditions. Examples include precipitation, temperature, streamflow, groundwater and reservoir levels, soil moisture and snowpack.
Indices are typically computed numerical representations of drought severity, assessed using climatic or hydrometeorological inputs including the indicators referenced on Drought.gov. They aim to measure the qualitative state of droughts on the landscape for a given time period. Indices are technically indicators as well.
Standardized Precipitation Index (SPI)
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Index (SPI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Index (SPI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Index (SPI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Index (SPI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Index (SPI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Index (SPI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Index (SPI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Index (SPI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Index (SPI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Index (SPI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
This SPI shows precipitation extremes over the 30 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
This SPI shows precipitation extremes over the 60 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
This SPI shows precipitation extremes over the 90 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
This SPI shows precipitation extremes over the 180 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
This SPI shows precipitation extremes over the 270 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
This SPI shows precipitation extremes over the 365 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset.
The ERA5 3-month Standardized Precipitation Index (SPI) is updated daily with a latency of 7–10 days.
A drought index combines multiple drought indicators (e.g., precipitation, temperature, soil moisture) to depict drought conditions. For some products, like the U.S. Drought Monitor, authors combine their analysis of drought indicators with input from local observers. Other drought indices, like the Standardized Precipitation Index (SPI), use an objective calculation to describe the severity, location, timing, and/or duration of drought.
Learn MoreDrought is defined as the lack of precipitation over an extended period of time, usually for a season or more, that results in a water shortage. Changes in precipitation can substantially disrupt crops and livestock, influence the frequency and intensity of severe weather events, and affect the quality and quantity of water available for municipal and industrial use.
Learn MoreStandardized Precip. Evapotranspiration Index (SPEI)
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
Dry Conditions
D4 (-2.0 or less)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is -2.0 or less, indicating exceptional drought (D4) conditions.
D3 (-1.9 to -1.6)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.9 to -1.6, indicating extreme drought (D3) conditions.
D2 (-1.5 to -1.3)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.5 to -1.3, indicating severe drought (D2) conditions.
D1 (-1.2 to -0.8)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -1.2 to -0.8, indicating moderate drought (D1) conditions.
D0 (-0.7 to -0.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between -0.7 to -0.5, indicating abnormally dry (D0) conditions.
Wet Conditions
W0 (0.5 to 0.7)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.5 to 0.7, indicating abnormally wet (W0) conditions.
W1 (0.8 to 1.2)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 0.8 to 1.2, indicating moderate wet (W1) conditions.
W2 (1.3 to 1.5)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.3 to 1.5, indicating severe wet (W2) conditions.
W3 (1.6 to 1.9)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is between 1.6 to 1.9, indicating extreme wet (W3) conditions.
W4 (2.0 or more)
The Standardized Precipitation Evapotranspiration Index (SPEI) value for this location is 2.0 or greater, indicating exceptional wet (W4) conditions.
This SPEI shows combined precipitation and evapotranspiration extremes over the 30 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
This SPEI shows combined precipitation and evapotranspiration extremes over the 60 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
This SPEI shows combined precipitation and evapotranspiration extremes over the 90 days prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
This SPEI shows combined precipitation and evapotranspiration extremes over the 6 months prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
This SPEI shows combined precipitation and evapotranspiration extremes over the 9 months prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
This SPEI shows combined precipitation and evapotranspiration extremes over the 12 months prior to the last updated date, when compared to the normal precipitation from 1991-2020, using the ERA5 dataset and the Hargreaves Potential Evapotranspiration (PET) equation.
Evaporative Demand Drought Index (EDDI)
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
ED4: Exceptional Drought
Compared to "normal" conditions, evaporative demand is greater than 98% to 100% of historical values. Learn more about these categories.
ED3: Extreme Drought
Compared to "normal" conditions, evaporative demand is greater than 95% to 98% of historical values. Learn more about these categories.
ED2: Severe Drought
Compared to "normal" conditions, evaporative demand is greater than 90% to 95% of historical values. Learn more about these categories.
ED1: Moderate Drought
Compared to "normal" conditions, evaporative demand is greater than 80% to 90% of previous values. Learn more about these categories.
ED0: Abnormally Dry
Compared to "normal" conditions, evaporative demand is greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
EW0: Abnormally Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1: Moderate Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2: Severe Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3: Extreme Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4: Exceptional Wet
Compared to "normal" conditions, current evaporative demand is in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
These EDDI products are generated from the ERA5 dataset. Please refer to the EDDI comparison page to view EDDI products generated from nClimGrid-Daily, ACIS, PRISM, GRIDMET, CPC and ERA5, standardized to the referenced period of 1991-2020.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
The Evaporative Demand Drought Index (EDDI) is an experimental drought monitoring and early warning guidance tool. It examines anomalous atmospheric evaporative demand (E0; also known as "the thirst of the atmosphere"). EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region. A particular strength of EDDI is in capturing the precursor signals of water stress at weekly to monthly timescales, which makes EDDI a strong tool for preparedness for both flash droughts and ongoing droughts.
The Drought.gov team produces this EDDI product with the Climate Engine tool and the ERA5 dataset, using a nonparametric distribution and Hargreaves PET.
Updates daily, with a latency of 2-4 days.
Updates daily, with a latency of 2-4 days.
Updates daily, with a latency of 2-4 days.
Updates daily, with a latency of 2-4 days.
Updates daily, with a latency of 2-4 days.
Updates daily, with a latency of 2-4 days.
Vegetation and Soil Moisture
Surface Soil Moisture: Wetness Percentile
Root Zone Soil Moisture: Wetness Percentile
Shallow Groundwater: Wetness Percentile
Unfavorable Conditions
Favorable Conditions
The Vegetation Health Index is a proxy characterizing vegetation health or a combined estimation of moisture and thermal conditions. Vegetation health is often used to estimate crop condition and anticipated yield. Values below 40 (pink/orange shades) indicate different levels of vegetation stress, and losses of crop and pasture production might be expected. Values above 60 (green/blue shades) indicate favorable conditions.
The Vegetation Health Index map updates weekly.
Soil moisture plays an important role in drought and flood forecasting, agricultural monitoring, forest fire prediction, water supply management, and other natural resource activities. Soil moisture observations can forewarn of impending drought or flood conditions before other more standard indicators are triggered.
Learn MoreFlash drought is the rapid onset or intensification of drought. Unlike slow-evolving drought, which is caused by a decline in precipitation, flash drought occurs when low precipitation is accompanied by abnormally high temperatures, high winds, and/or changes in radiation. These sometimes-rapid changes can quickly raise evapotranspiration rates and remove available water from the landscape.
Learn MoreDrought can reduce the water availability and water quality necessary for productive farms, ranches, and grazing lands, resulting in significant negative direct and indirect economic impacts to the agricultural sector. Monitoring agricultural drought typically focuses on examining levels of precipitation, evaporative demand, soil moisture, and surface/groundwater quantity and quality.
Learn MoreDrought can result in reduced growth rates, increased stress on vegetation, and alterations or transformations to the plant community and/or the entire ecosystem. During periods of drought, plants increase their demand for water through increased evapotranspiration and longer growing seasons.
Learn MoreA drought index combines multiple drought indicators (e.g., precipitation, temperature, soil moisture) to depict drought conditions. For some products, like the U.S. Drought Monitor, authors combine their analysis of drought indicators with input from local observers. Other drought indices, like the Standardized Precipitation Index (SPI), use an objective calculation to describe the severity, location, timing, and/or duration of drought.
Learn MoreFlash drought is the rapid onset or intensification of drought. Unlike slow-evolving drought, which is caused by a decline in precipitation, flash drought occurs when low precipitation is accompanied by abnormally high temperatures, high winds, and/or changes in radiation. These sometimes-rapid changes can quickly raise evapotranspiration rates and remove available water from the landscape.
Learn MoreDrought can reduce the water availability and water quality necessary for productive farms, ranches, and grazing lands, resulting in significant negative direct and indirect economic impacts to the agricultural sector. Monitoring agricultural drought typically focuses on examining levels of precipitation, evaporative demand, soil moisture, and surface/groundwater quantity and quality.
Learn MoreDrought can result in reduced growth rates, increased stress on vegetation, and alterations or transformations to the plant community and/or the entire ecosystem. During periods of drought, plants increase their demand for water through increased evapotranspiration and longer growing seasons.
Learn More