Climate Matters•February 21, 2024
Snowfall Trends
KEY CONCEPTS
Warmer air holds more moisture, which can fall as snow when temperatures are below freezing.
Winter is the fastest-warming season for most of the U.S., resulting in less snow in most places.
Climate Central assessed snowfall trends in 2,041 U.S. locations.
Nearly two-thirds (64%) of locations now get less snow than they did in the early 1970s. Another 731 locations (36%) have seen snowfall increase.
Climate change affects the timing, location, and amount of snowfall — as well as spring snowmelt patterns — in complex ways.
We review historical and projected future snow dynamics for the western U.S., Northeast, Northern Great Plains, and Great Lakes regions — and their impacts on people and ecosystems.
Snowfall in a warming world
Snow keeps our planet cooler, makes up more than 50% of runoff that replenishes reservoirs and groundwater across the western U.S., and underpins local economies and cultures from coast to coast.
Two basic conditions are needed to produce snow: both freezing temperatures and moisture in the atmosphere. How are these conditions affected by climate change?
Fewer freezes. Winter is the fastest-warming season for most of the U.S., leading to a drop in the annual number of freezing nights since 1970 in 204 locations. With continued warming, the number of days below 32°F is expected to decline further in the coming decades.
More moisture. Our warming atmosphere holds about 4% more moisture per 1°F of temperature rise. But where that moisture falls, and whether it’s more likely to fall as rain or snow, varies by region.
National snowfall trends
Climate Central used long-term snowfall observations from 2,041 U.S. monitoring stations to assess changes in annual snowfall from 1970 to 2023.
Over that period, nearly two-thirds (64%, or 1,301) of locations now have less snowfall than they did in the early 1970s, while 731 stations (36%) have experienced an increase in snowfall. The rest experienced no change.
Less snow can limit water supplies derived from snowpack — especially in parts of the western U.S. that rely on snowpack for water supplies. Snow drought can also take a toll on regional recreation and tourism industries by decreasing snow at ski areas.
With continued warming, the amount of water stored in snowpack is projected to decline further across the U.S. — especially in coastal southern Alaska and the mountain ranges of California and the Northwest.
Regional snow trends
Climate change can affect the timing, location, and amount of snowfall, as well as the dynamics of snowmelt. But these changes and their wide-ranging impacts vary among regions.
Western U.S.
The amount of mountain snowpack and the timing of snowmelt largely determine the supply of water to rivers and reservoirs in the western U.S. during the high-demand spring and summer.
But since the mid-20th century, the western U.S. has experienced declining snowpack, earlier snowmelt and streamflow, and a shift toward less precipitation falling as snow.
A 2018 study shows that decades of shrinking snowpack has reduced snow-derived freshwater in the West by 15-30% since 1955.
A 2020 study identified the western U.S. as a global hot spot for snow drought. The region experienced a 28% increase in the duration of snow droughts from 1980 to 2018.
In addition to reducing water supplies available for municipalities, irrigation, industry and ecosystems, reduced mountain snowpack and earlier snowmelt can also increase wildfire risk in western forests with abundant fuels.
In the Southwestern U.S., declining snowpack, earlier spring snowmelt, and higher rainfall-to-snowfall ratios all exacerbate the risk of drought in the region.
In the San Joaquin and Colorado River Basins, irrigated agriculture and food production face risks from a mis-match in the timing of (earlier) snowmelt runoff and growing season water demand.
Northeast
The Northeast has experienced an increase in the proportion of winter precipitation falling as rain rather than snow. This trend is projected to continue over the 21st century with a northward shift in the snow-rain transition zone.
A 2018 study projects both a decrease in the overall frequency of Northeast snowstorms this century, as well as greater likelihood that the heaviest snowstorms will bring more snow when temperatures are still cold enough.
The multi-billion dollar winter recreation industry is an important part of the regional economy and culture. The industry already takes an economic hit during low snow years, and future emissions scenarios suggest that the winter recreation season is likely to become shorter and smaller throughout much of the Northeast as winters continue to warm.
Great Lakes Region
The Great Lakes hold 90% of the freshwater in the U.S., and support both recreation and cultural heritage deeply rooted in the surrounding communities.
Although snowfall is often associated with mountains, other features, including large lakes, can also lead to intense local snowfall. In the Great Lakes region, lake effect snow occurs when cold air from the north moves across the relatively milder open water of the Great Lakes.
As the planet has warmed, so have the Great Lakes. Despite year-to-year variability, long-term records show a 25% decrease in basin-wide ice cover as well as a trend toward fewer frozen days across the Great Lakes since 1973.
Longer periods of open water lead to more evaporation and to an increase in lake effect snow. Looking to the future, projections suggest that lake effect snow will still occur in a warming world, but by the late 21st century, we can expect a shortened lake effect snow season.
Northern Great Plains
Warming in the Northern Great Plains has led to shorter snow seasons and a decline in snowpack water storage.
Regional streamflow, especially in late summer, is highly dependent on snowpack. Lower and more variable snow-fed streamflows impact riparian and aquatic ecosystems, as well as the local economies and recreational industries that depend on them.
Mountainous areas of the Northern Great Plains also face snow-dependent economic and ecological risks due to climate change, including shorter skiing and snowmobiling seasons and fewer visitors.
LOCAL STORY ANGLES
What’s the snow forecast where you live?
The National Weather Service’s Winter Page provides maps and forecasts for snow and ice in your area. Their Winter Weather Desk provides twice-daily local forecasts for snow and freezing rain.
Regional snowfall resources
NOAA's Regional Snowfall Index (RSI) ranks snowstorm impacts based on the storm area, amount of snowfall, and affected population. The RSI covers the six easternmost climate regions.
The Snow Telemetry (SNOTEL) Network of over 900 automated data collection sites located mainly in high-elevation watersheds in the western U.S. and in Alaska. The National Weather and Climate Center’s Water and Climate Information System makes this and related data available through chatting tools, report generators and interactive maps.
The National Snow and Ice Data Center (NSIDC) is focused on the science of Earth’s changing cryosphere, and manages scientific data on snow, ice, glaciers, frozen ground, and related climate dynamics.
The Rutgers University Global Snow Lab provides maps, graphic products and tabular data on Northern Hemisphere snow cover.
How is climate change impacting winter activities and tourism near you?
Check out National Integrated Drought Information System maps showing current drought conditions at reservoirs, ski areas, and national parks across the U.S. Climate Central’s report On Thin Ice covers the impacts of warming winters on America’s cold-weather sports economy.
Tools for reporting on winter weather events near you:
Warmer temperatures can make winter storms more complicated, with sleet and freezing rain. Criteria for winter storm watches, advisories, and warnings can vary by region so check out your local National Weather Service office. The NWS also provides helpful information on how to stay safe in winter conditions, wind chill charts, and an explanation of the polar vortex. And the National Snow and Ice Data Center (NSIDC) has just about everything you need to know about snow.
FIND EXPERTS
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
METHODOLOGY
The general change (more/less) in total annual snowfall (1970-2023) was calculated for a list of 2,041 Global Historical Climatology Network daily U.S. weather stations using data from the Applied Climate Information System. Each station received an annual average of at least 5” of total snowfall over the 54-year period analyzed.