Fastest-Warming Seasons

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KEY CONCEPTS

• As our climate heats up, all four seasons are warming — but at different rates across the U.S.

• Winter was the fastest-warming season for 76% (185) of the 245 U.S. locations analyzed by Climate Central.

• Locations with the fastest winter warming since 1970 were found from coast to coast, but were clustered in the Northeast, Southeast, and Ohio Valley regions — disrupting snowfall patterns.

• Fall and spring were the fastest-warming seasons for many (31) western U.S. locations, raising risks of longer pest and allergy seasons as well as earlier snowmelt, which can stretch water supplies thin.

• Some locations in the West and Northwest saw summers warm most quickly, increasing the risks associated with wildfire, heat extremes, and poor air quality.

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Warming Planet, Warming Seasons

Season length and temperatures vary naturally from year to year. But the unprecedented rate of global warming observed since the 1950s, due primarily to emissions of heat-trapping gases from burning fossil fuels, is influencing long-term warming trends in each season. 

Climate Central analyzed seasonal warming trends since 1970 in 245 U.S. locations to see how much warming we’ve experienced in each season — and how quickly. Seasonal warming can have widespread effects on health, water supplies, fire seasons, agriculture, and more.

Winter Warming

The most rapid warming in the U.S. has generally occurred when and where it’s usually the coldest, including at night, in northern parts of the country, and during winter.

Winter was the fastest-warming season for the majority 76% (185) of the 245 U.S. locations analyzed by Climate Central. Locations with the fastest winter warming since 1970 were found from coast to coast, but were clustered in the Northeast, Southeast, and Ohio Valley regions.

• Warming winters can disrupt snowfall patterns, which can in turn limit snowfed water supplies critical for people, agriculture, and ecosystems. Limited snowpack accumulations reduce the amount of water stored for drinking, hydropower, and irrigation.

• Regional economies and cultures that depend on winter recreation can also feel the effects of winter warming.

• Yields of high-value fruit crops that require a minimum number of winter chill hours can also be impacted by rising winter temperatures. 

• While warmer winters can reduce energy demands for home heating, those savings can be offset by increased cooling demand during the warming summer months. 

Spring and Fall Warming

Fall and spring were the fastest-warming seasons for many (31) western U.S. locations included in Climate Central’s analysis. 

• Warmer springs can cause mountain snowpack to melt earlier — meaning snowfed water supplies need to stretch even longer into the warmest months when water demand peaks. 

• An early spring and early last freeze can increase the risks of longer pest, pollen, and allergy seasons — all of which can have serious consequences for ecosystems and human health. 

• Warmer spring and fall can also mean longer growing seasons. Although some plants and animals may benefit, longer growing seasons can also increase pests and weeds, lead to water and heat stress in rainfed crops, and disrupt farmers’ planting, irrigation, pest management, and harvest schedules. 

• Spring warming can also disrupt the timing of ecologically-important events like leaf growth and flower blooms, pollination, and migration. For example, some migratory bird species are not keeping pace with the earlier arrival of spring in the eastern U.S., potentially impacting their food availability and breeding success.

Summer Warming

Some locations in the West and Northwest saw summers warm most quickly. 

• Rapid fall and summer warming contributes to recent increases in wildfire intensity, size, and season length in the western U.S.

• Overall summer warming also contributes to the observed increase in the number of local extremely hot days, as well as the occurrence of hazardous humid heat. 

• The health risks from warmer summers extend from heat extremes to air quality, as rising summer temperatures also contribute to a buildup of pollutants in the air we breathe. 

• Warmer summers also mean greater cooling demand and higher energy costs. According to the EPA, summer electricity use in the average American home has nearly doubled since 1973, along with a rise in cooling degree days. 

LOCAL STORY ANGLES

Which warming impacts are most important in my area?

The EPA’s 2021 report, Seasonality and Climate Change, reviews the evidence of shifting seasons across the U.S. and discusses implications for each region and season. Explore EPA’s full set of Climate Change Indicators for more evidence and impacts of climate change across the U.S. The most recent National Climate Assessment (released in 2023) assesses climate impacts for 10 U.S. regions. 

What weather can we expect at the start of 2025?

NOAA’s one-month to three-month outlooks assess the probability of exceeding thresholds of above and below normal temperature and precipitation in the US. Access February 2025’s temperature, precipitation, and drought outlook for an indication of near-term conditions near you. 

CONTACT EXPERTS

William Anderegg, PhD
Professor, School of Biological Sciences, University of Utah
Director, Wilkes Center for Climate Science and Policy, University of Utah
Contact: anderegg@utah.edu  
Related expertise: Climate change impacts on forest ecosystems, wildfires, and pollen seasons

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

Trends for meteorological seasons are calculated using seasonal average temperature data between 1970 and 2024 (data from the Applied Climate Information System). Stations with large gaps of missing data (Hazard, Ky. and Wheeling, W.Va.) were removed from this analysis.

Important changes to our Climate Matters stations beginning January 1, 2025:

• Due to various weather station closures, six cities will now receive data from different weather stations than those we’ve used in the past: Dothan, Ala.; Glendive, Mont.; Hagerstown, Md.; Hattiesburg, Miss.; Idaho Falls, Idaho; and Tyler, Texas. 

• We will no longer produce local graphics for Panama City, Fla. 

• We are now producing local graphics for Rochester, Minn.