Climate Matters
Cooling Schools in a Hotter Climate
As kids head back to school, cooling demand is on the rise across the U.S.
Climate Matters•August 27, 2025
2025 Fall Package
KEY FACTS
September 1 is the start of meteorological fall. The season has warmed in every county across the contiguous U.S. since 1970 — and is warming fastest in the Southwest.
Fall has warmed in 237 U.S. cities — by 2.8°F on average from 1970 through 2024.
Unusually warm fall days now happen more often in 238 cities, or 98% of the 243 cities analyzed.
A warmer fall season prolongs risks of heat-related illness, wildfire, allergies, and more.
This Climate Matters analysis is based on open-access data from the National Oceanic and Atmospheric Administration (NOAA). See Methodology for details.
Hurricane season reporting resources
Near-record warm oceans have led to continued predictions for an above-normal 2025 Atlantic hurricane season, which extends through November 30 and historically peaks around September 10.
NOAA’s National Hurricane Center monitors current conditions. Their Hurricane Preparedness hub has information to help communities stay safe before, during, and after hurricanes.
Reporting resources on climate change and hurricanes:
Warm oceans fuel stronger hurricanes. Climate Central’s new Climate Shift Index: Tropical Cyclones tool quantifies the impact of climate change hurricane wind speeds in real-time.
Climate Central’s Extreme Weather Toolkit: Tropical Cyclones provides quick facts and a collection of reporting resources on hurricanes and climate change.
NOAA regularly updates a summary of the science on Global Warming and Hurricanes and offers a hurricane season Media Resource Guide.
Climate Central’s FloodVision®supports storm surge communication with photorealistic, street-level coastal flooding visuals for hundreds of coastal communities along the East and Gulf Coasts.
Falling leaves, rising temperatures
This summer’s heat is likely to linger through fall with above-normal temperatures expected across the U.S. from September through November.
This year is not an exception. It’s part of a longer warming trend. All four seasons have been heating up in the U.S. as the planet warms due to heat-trapping pollution.
A warmer fall season means that the risky heat, high cooling demand, wildfires, and allergies of summer linger later into the year — affecting health, ecosystems, and the economy.
To understand how these warming trends affect local conditions, Climate Central analyzed the last 55 years (1970–2024) of fall temperature data in 243 U.S. cities (see Methodology).
Fall is heating up everywhere — especially in the Southwest.
The fall season has warmed in every county across the contiguous U.S. since 1970.
The Southwest and Northern Rockies and Plains regions have experienced the most fall warming.
U.S. Climate Region | Change in average fall temperature (°F), 1970-2024 |
|---|---|
Southwest | 4.0 |
Northern Rockies and Plains | 3.5 |
Upper Midwest | 3.3 |
South | 3.0 |
Northwest | 2.8 |
Northeast | 2.8 |
West | 2.6 |
Ohio Valley | 2.1 |
Southeast | 1.9 |
Fall is warming in 237 U.S. cities
Average fall temperatures have increased since 1970 in 237 (98%) of the 243 locations analyzed.
On average, cities that experienced an increase in temperatures have warmed by an average of 2.8°F.
Some 103 (42%) of those locations have warmed by 3°F or more since 1970.
The top five fall warming locations were: Reno, Nev. (7.7°F); El Paso, Texas (6.5°F); Las Vegas, Nev. (6.2°F); Tyler, Texas (5.8°F); and Tucson, Ariz. (5.8°F).
More hotter-than-normal fall days in 238 U.S. cities
The warming season is also reflected in the number of additional fall days with temperatures that exceeded the 1991-2020 average for the season and location.
Since 1970, 238 (98%) of the locations analyzed have seen an increase in the annual number of days above their normal fall temperatures.
Almost half of the cities analyzed (119, or 49%) now experience at least two more weeks’ worth of above-normal fall days than in 1970.
Fall warming affects health, wildfire, agriculture, and more
When summer heat lingers into fall, it can extend the health risks to athletes from extreme heat or to weather-exposed workers from humid heat. Those most at risk for heat-related illness include children.
An extended peak heat season brings higher cooling demand. Nationwide, fall cooling degree days have increased significantly since 1970. Keeping schools cool is a growing challenge as our climate warms, especially for those in urban heat islands. When air conditioners run later into the year, energy costs and heat-trapping emissions both increase.
Hotter falls also mean a longer wildfire season. Wildfire risk, as measured by the frequency of hot, dry, windy fire weather, is getting longer and more intense — particularly in the western U.S.
A lengthened wildfire season puts human health and safety at risk. Homes, roads, power lines, and other critical infrastructure across the U.S. face exposure to potential wildfire damage. Wildfire smoke combined with climate change-fueled heat can further worsen air quality, posing additional risk to human health.
Conditions that trigger fall color each year are shifting with climate change, potentially impacting the ecological and economic value linked to fall foliage.
Warmer temperatures during the fall also extend the growing season, which can benefit some agricultural crops — but also contribute to a longer and more intense allergy season for the millions of Americans suffering with allergies and asthma.
Warming also allows disease-carrying insects such as mosquitoes to linger later into the fall. Fall warming can also disrupt the timing of ecologically important events like bird migrations, hibernation, and fruit ripening.
Warmer growing seasons can also increase the risk of water stress in plants, especially in drought-prone regions of the West and Southwest that have experienced the most fall warming.
LOCAL STORY ANGLES
How is heat affecting local health, and who is most vulnerable?
The CDC maps heat-related illnesses in its heat and health tracker. To identify the most vulnerable counties check out this extreme heat vulnerability mapping tool that combines NOAA projected heat events and CDC's Social Vulnerability Index.
What’s the air quality in your local area?
AirNow, a partnership of multiple government agencies, offers a wildfire and smoke tracking map, as well as interactive air quality maps in English and Spanish, and resources focused on air quality and health. The National Allergy Bureau’s Aeroallergen Network provides station-level allergen reports across the U.S.
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
Average temperatures and days above normal were calculated for each meteorological fall (September, October, November) from 1970 to 2024 using data obtained from the Applied Climate Information System, which is developed, maintained, and operated by NOAA’s Regional Climate Centers. Fall days above normal are defined as the number of days where the average temperature was above the 1991-2020 NOAA/NCEI climate normal for the season.
The map of the contiguous U.S. shows the change in average fall temperatures by county since 1970 with data from NOAA/NCEI’s Climate at a Glance. Previous versions of the Climate Matters map graphic showing the change in seasonal average temperature displayed the data by climate division. Note that although Connecticut recently replaced their counties with planning regions, data for Connecticut is displayed by county because NCEI data are not yet available for Connecticut’s planning regions.
Climate Central's local analyses include 247 stations. For reported data summaries of historical (1970-2024) observed fall warming trends based on linear regression, however, only 243 stations are included due to data completeness measures that were not met by four stations: Bend, Ore.; Twin Falls, Idaho; Hazard, Ky.; and Wheeling, W.Va.