Climate Matters•November 16, 2022
Fastest Warming Seasons
KEY CONCEPTS
As our climate warms, all four seasons are warming too—but at different rates across the U.S.
Winter was the fastest warming season for 74% of the 246 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 and the Great Lakes region—disrupting snowfall patterns.
Fall and spring were the fastest warming seasons for many western U.S. locations, raising risks of longer pest and allergy seasons as well as earlier snowmelt stretching water supplies thin.
Some locations in Washington, Oregon, Texas, and Florida saw summers warm most quickly, increasing the risks associated with wildfire, heat extremes, and poor air quality.
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, is influencing long-term warming trends in each season.
Climate Central analyzed seasonal warming trends since 1970 in 247 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 74% (182) of the 246 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 and the Great Lakes region.
Warming winters can disrupt snowfall patterns, which can in turn limit snowfed water supplies critical for people, agriculture, and ecosystems.
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 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 ecosystem 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 boost production of 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 Washington, Oregon, Texas, and Florida saw summers warm most quickly.
Rapid fall and summer warming contributes to recent increases in wildfire intensity, frequency, 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.
POTENTIAL 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 2018) assesses climate impacts for 10 U.S. regions.
What’s the outlook for winter near me? How will that affect local heating energy use?
NOAA’s 2022-2023 Winter Outlook provides temperature, precipitation and drought forecasts for the winter ahead. The outlook predicts warmer-than-average temperatures for the Southwest, the Gulf Coast, and the eastern seaboard due in part to the third consecutive La Niña winter. The U.S. EIA’s 2022-2023 Winter Fuels Outlook forecasts home energy use and expenditures across the country.
LOCAL EXPERTS
The SciLine service, 500 Women Scientists or the press offices of local universities may be able to connect you with local scientists who have expertise on seasonality and climate change. The American Association of State Climatologists is a professional scientific organization composed of all state climatologists.
NATIONAL EXPERTS
Theresa Crimmins, PhD
Director, USA National Phenology Network
Research Professor, University of Arizona
Contact: theresa@usanpn.org
Related expertise: plant and animal phenology (seasonal events)
Crystal A. Kolden, PhD
Associate Professor
University of California, Merced
Contact: ckolden@ucmerced.edu
Related expertise: Western U.S. wildfire risk
Karin Gleason
Monitoring Section Chief
NOAA's National Centers for Environmental Information (NCEI)
Contact: karin.l.gleason@noaa.gov
Related expertise: Climate monitoring, drought, weather extremes
Alyssa Rosemartin
Partner and Application Specialist
USA National Phenology Network
School of Natural Resources and the Environment, University of Arizona
Contact: alyssa@usanpn.org
*Available for interviews in Spanish and English
METHODOLOGY
Trends for meteorological seasons are calculated using seasonal average temperature data between 1970 and 2022 (data from the Applied Climate Information System). For clarity and the ability to compare different seasons, we have omitted the annual data points and displayed only the linear trends over time. Your local seasonal trends may vary from your state seasonal trends due to a variety of factors, including microclimate influences. Stations with large gaps of missing data were removed from this analysis.