Climate has long ruled the fortunes of winter destinations dependent on snow for skiing and other winter sports. As greenhouse gas emissions continue to rise, the world continues to warm. Last year was the third warmest in the instrumental record and the warmest year that was not experiencing an El Niño state. Seasonally, winter has warmed the fastest, causing those in the winter sports industry to consider how to manage future changes in snow season length, and amount, reliability, and quality of accumulated snowfall.

The ski industry is already hurting from the effects of climate change, with more unpredictable and warmer winters making it increasingly difficult for places dependent upon steady revenue from snow-seeking tourists. Ski operators have proved able to adapt to some extent, such as making up for lost snow through artificial production. However, snowmaking requires energy to run equipment, significant water resources, and sub-freezing temperatures. Winter tourists have had to adjust as well, varying the time and frequency of their travel.

Average snowfall is influenced by a resort’s elevation and the frequency of winter storms and precipitation. But, it’s just not going to snow if it’s warm outside — days below the freezing temperature of 32^oF signal whether a resort town can potentially support snowfall for ski days. Making snow doesn’t get resorts off the hook either. The ideal temperature for artificial snowmaking is an even colder 28^oF, dependent on humidity. As the climate continues to warm, the number of days that can support snowfall are expected to decrease, and ski resort towns could lose valuable tourism traffic. If emissions continue to rise at the same pace they did in the first decade of this century, places that will be especially plagued by temperature rise include Lake Tahoe, Sun Valley, and Montana’s Whitefish Mountain Resort. (Figure 1).

We estimated county-level changes in climate under two long-term climate change scenarios: a high global emissions scenario and a scenario of moderate emissions that roughly corresponds to what countries agreed to in the Paris climate accord. Results span three future time periods: the next 20 years (2020-2039), mid-century (2040-2059), and late century (2080-2099). These were compared to temperature data from 1981-2010, as calculated by the National Climatic Data Center. Below we summarize the results for 11 counties home to the nation’s top ski towns.

We estimated county-level changes in climate under two long-term climate change scenarios: a high global emissions scenario and a scenario of moderate emissions that roughly corresponds to what countries agreed to in the Paris climate accord. Results span three future time periods: the next 20 years (2020-2039), mid-century (2040-2059), and late century (2080-2099). These were compared to temperature data from 1981-2010, as calculated by the National Climatic Data Center. Below we summarize the results for 11 counties home to the nation’s top ski towns.

Truckee, California: The gateway to downhill and cross-country resorts of North Lake Tahoe, Truckee is located in Nevada County. The name “Nevada” is Spanish for “snow-capped,” but winter temperatures in the county are projected to average just shy of 50^oF by late century under a high emissions scenario, which could leave mountainous areas like Donner Summit covered in brown, not white. By 2100, Truckee can expect only eight days per year at or below 32^oF, on average, an 80% loss compared to historic conditions. Under a moderate emissions scenario, the county is on track for an average of 20 days of cold temperatures each year by late century.

 Whitefish, Montana: Slopes around Big Mountain feature abundance of long, wide open paths with ample pockets of steep and deep terrain. The glaciers that formed the broad, flat valley surrounded by mountains — Flathead County’s namesake – are losing mass and retreating as the region warms. From 1981 to 2010, an average of 162 days each year had temperatures at or below freezing. By midcentury, the county can expect about four months’ worth of these cold days, on average. That shrinks to seven weeks by late century. Under a moderate emissions scenario, cold days diminish more slowly. The county can expect nearly 15 weeks of subfreezing temperatures in late century.

Park City, Utah:  Summit County, nestled high in the Wasatch Mountains, includes 39 of the highest peaks in Utah. Park City, which hosts the Sundance Film Festival, is bordered by Deer Valley Resort and Park City Mountain Resort and sits just south of the nearly 400-acre Utah Olympic Park. An average of 194 days each year between 1981 and 2010 were at or below freezing, but that figure could be cut in half by late century if emissions continue to rise. The county is projected to experience an average of 100 days at or below freezing by 2100, compared to 141 days under a moderate emissions scenario.

Bend, Oregon: Mount Bachelor currently offers one of the longest ski seasons in the U.S., stretching from mid-November through late May. Nearby Bend has hotels, restaurants, and an abundance of craft breweries to sample in between runs. Deschutes County can expect its annual share of days at or below freezing to fall from a historical average of 161 to just 84 – equivalent to 12 weeks — by late century. Winter average temperatures, historically around 32^oF, are projected to be just shy of 40^oF by 2100. Under a moderate emissions scenario, the county can expect about four months’ worth of sub-freezing days per year in late century.

Ketchum, Idaho:  The light, dry powder and ample sun in Idaho’s Wood River valley attracted the Austrian founder of Sun Valley Resort, established in 1936, outside artsy Ketchum. Today the resort boasts the largest computerized snowmaking system in North America. Under a high emissions scenario, Blaine County can expect a 40% decline in the number of days at or below freezing by late century, falling from a historical annual average of more than 200 days to about 120. Under a moderate emissions path, the annual average by late century is 159 days. Average winter temperatures will still allow for snow under a high emissions scenario. By 2100, they can be expected to increase to 30^oF from a historical average of 20^oF.

Telluride, Colorado:  Peaks of at least 14,000 feet surround three sides of Telluride, a former mining town that is situated in a box canyon. Telluride Ski Resort maintains well-groomed trails in the notoriously steep and jagged San Juan Mountains. San Miguel County experienced an average 178 days of temperatures at or below 32^oF each year between 1981 and 2010. By late century the number of sub-freezing days declines by 41%, under a high emissions scenario, and average winter temperatures are projected to rise to 37 ^oF.  Under a more moderate emissions scenario, the county can expect nearly 20 weeks of cold temperatures each year, on average, by late century.

North Conway, New Hampshire:  Tucked into the White Mountain National Forest, the village of North Conway gives visitors easy access to New Hampshire’s Mount Washington Valley. Attitash, King Pine Ski Area and Wildcat Mountain Ski Area are among New England’s most popular downhill terrain. Carroll County can expect to retain its sub-freezing winter average temperatures through late century, but it will experience 36% fewer 32^oF days. The county can expect an average of 15 weeks per year at or below freezing by late century under a high emissions scenario, compared to about 23 weeks of those temperatures from 1981 to 2010. Under a moderate emissions scenario, the county is on pace to experience an annual average of 19 weeks of cold temperatures by late century.

Jackson, Wyoming: The Jackson Hole Valley’s namesake ski resort in Teton Village features the longest vertical rise of any ski lift in the nation, with a 4,139-foot journey to the top of Rendezvous Mountain. The expert trails here are known for their fierce steeps and chutes, suited to advanced skiers. Teton County can expect a more moderate increase in temperatures, with annual winter averages rising from a historical 15 ^oF to 24^oF. The average annual number of sub-freezing days shifts from 244 to 160 by late century, a 35% decline, under high emissions. Under a moderate emissions scenario, the county can expect 200 days of cold each year by late century.

Taos, New Mexico:  In remote northern New Mexico, Taos Ski Valley is anchored by Kachina Peak, a summit known for steep powder skiing.  Scant snowfall and mild winter weather in recent years has pushed back the traditional opening date of the resort, but operators have adapted by expanding their capacity for snowmaking. Taos County can expect an average of 141 days per year of sub-freezing temperatures through late century under a high emissions scenario, compared to 198 32 ^oF days on average from 1981 to 2001. The county is on track for 170 days each year, on average, of cold days by late century under a moderate emissions scenario.

Stowe, Vermont: Mount Mansfield, the state’s highest peak, overlooks the town of Stowe. It’s known for holding some of the oldest ski trails in the country. Stowe Mountain Resort also provides access to Spruce Peak, located so far north that on clear days you can see over the U.S. border. Temperatures in Lamoille County will remain cold enough that high-elevation destinations should be safe bets for snowmaking. The county can expect a 28% decline in the annual average amount of sub-freezing days, slipping from the equivalent of 28 weeks to around 20 under a high emissions scenario, and 24 weeks under a moderate emissions scenario.

Breckenridge, Colorado:  Breckenridge hosted the first World Snowboarding Championships in 1986, and its nearly 3,000 acres of skiable terrain has long been a top choice for winter tourists. “Breck,” as it is affectionately known, boasts one of the highest summit elevations in the U.S. From 1981 to 2010, Summit County averaged 262 annual days of sub-freezing temperatures and winter temperatures of 18^oF. Under a high emissions scenario, Summit County can expect late century winters to feel about 10^oF warmer with 25% fewer average annual days at or below 32^oF.  The average annual amount of cold days under a moderate emissions scenario by late century is 230.