Climate Matters•February 26, 2025
2025 Spring Package
KEY CONCEPTS
Climate Central analyzed 55 years of temperature data and found that meteorological spring (March - May) has warmed across the U.S. from 1970 to 2024.
The spring season has warmed in 234 (97%) of the 241 U.S. cities analyzed — by 2.4°F on average.
Unusually warm spring days now happen more often. Four out of every five cities now experience at least one more week of warmer-than-normal spring days than in the 1970s.
Spring has warmed the most across the southern tier of the country, particularly in the Southwest.
Spring warming can prolong seasonal allergies, worsen wildfire risk, and limit snow-fed water supplies.
This Climate Matters analysis is based on open access data from the National Oceanic and Atmospheric Administration (NOAA). See Methodology for details.
Explore county-level data on spring warming from 1970-2024.
Warming world, warming seasons
Like all other seasons, spring is getting warmer across the U.S. National warming trends reflect global warming caused by heat-trapping pollution mainly from burning coal, oil, and methane gas for electricity, transportation, heating, and more.
Climate Central analyzed spring average temperature data from 241 U.S. locations to see how and where the spring season (March, April, May) has warmed from 1970 to 2024 (see Methodology).
Spring is warming in 234 U.S. cities
Over the last 55 years, average spring temperatures have increased across the U.S.
Average spring temperatures increased in 234 (97% of 241) cities analyzed since 1970.
Over that period, spring warmed by 2.4°F on average across these 234 cities.
Average spring temperatures warmed by 3°F or more in 71 cities.
Spring warmed the most, on average, in locations across the southern tier of the country: Southwest (3.4°F), South (2.7°F), Southeast (2.5°F), and Ohio Valley (2.5°F).
The top spring warming locations were: Reno, Nev. (6.8°F); El Paso, Texas (6.4°F); Las Vegas, Nev. (6.1°F); Tucson, Ariz. (5.8°F); Albany, Ga. (5.3°F); Chattanooga, Tenn. (5.3°F); and Phoenix, Ariz. (5.3°F).
More unusually warm spring days
The warming season is also reflected in the growing number of spring days above the 1991-2020 spring normal temperature for each location.
Since 1970, the average number of warmer-than-normal spring days has increased in 236 (98%) of the 241 locations analyzed.
The majority of locations (80%, or 194) now experience at least seven additional warmer-than-normal spring days than they did in the early 1970s.
The rise in warmer-than-normal spring days was highest among locations in the Southwest (19 more days on average), West and Southeast (both 15 more days on average), and South (14 more days on average).
The cities with the largest increase in warmer-than-normal spring days since 1970 were: El Paso, Texas (39 more days); Tampa, Fla. (37 more days); Reno, Nev. (36 more days); Tucson, Ariz. (35 more days); and Albany, Ga. (33 more days).
Spring warming can…
Prolong seasonal allergies. Warmer, shorter winters mean an earlier spring thaw and later fall freeze. This warming trend gives plants more time to grow and release allergy-inducing pollen earlier in spring and later into fall. That’s bad news for people with seasonal allergies — about one-quarter of adults and one-in-five children in the U.S.
Worsen wildfire risk. Fire weather — a combination of high heat, low humidity, and strong winds — helps wildfires to start and spread. Climate Central analysis indicates that fire weather conditions have grown longer and more intense across the U.S. since 1973. Spring is the fastest-growing fire weather season (1973-2023) in nearly every major U.S. region, particularly in the Southwest and West.
Stress western water supplies. Spring meltwater and runoff is a critical source of water that refills reservoirs, irrigates crops, and helps meet peak water demand across the western U.S. Warming winters can reduce snowfall and mountain snowpack, while warming springs can contribute to earlier snowmelt. The water deficit brought by earlier spring snowmelt has critical consequences for hydropower, agriculture, and drinking water supplies.
Boost disease-carrying pests. Cold winters and springs can keep the populations of disease-carrying pests like mosquitoes in check. But warmer winters and shoulder seasons can extend mosquito seasons and worsen pest-related health risks.
Lengthen growing seasons. Spring is not only warming but also shifting. As warm weather cuts into colder months, growing seasons last longer. A longer growing season can bring opportunities and challenges for agriculture, depending on the location, ecosystem, and other factors such as water supply.
Shift planting zones that guide farmers and gardeners. As the U.S. warms, plant hardiness zones are shifting north, changing which plants can grow and thrive in different parts of the country. These trends are projected to continue throughout this century with continued high levels of heat-trapping pollution.
LOCAL STORY ANGLES
What’s the status of spring near you?
The USA National Phenology Network provides a suite of tools to track the status of spring across the country including historical, real-time, and forecasted phenology maps. These tools can be used to forecast invasive species and pests, allergy outbreaks, and inform agricultural calendars.
How is allergy season in your area affected by warmer springs?
Explore Climate Central’s analysis of long-term changes in the freeze-free growing season in 203 U.S. cities. Find out how your city ranked in the Asthma and Allergy Foundation of America’s annual report on the top 100 U.S. Allergy Capitals. Search for a local allergen report or sign up for pollen level alerts through the National Allergy Bureau.
See the influence of climate change on warm spring days near you.
Climate Central’s Climate Shift Index map tool quantifies the influence of climate change on daily temperatures across the U.S. and around the globe in real time.
CONTACT EXPERTS
Theresa M. Crimmins, Ph.D. (she/her)
Director, USA National Phenology Network
University of Arizona
Related expertise: plant phenology and climate change
Contact: theresam@arizona.edu
Toby R. Ault, Ph.D.
Associate Professor
Cornell University
Relevant expertise: spring onset dynamics
Contact: toby.ault@cornell.edu
Carlos Carrillo, Ph.D.
Research Associate
Cornell University
Relevant expertise: spring onset forecasting and drought predictability
Contact: carrillo@cornell.edu
*Available for interviews in Spanish
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 spring (March, April, May) 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. Spring days above normal are defined as the number of days with average temperatures above the 1991-2020 NOAA/NCEI climate normals.
Climate Central's local analyses include 247 stations. For reported data summaries based on linear regression, however, only 241 stations are included due to data completeness measures that were not met by six stations: Bend, Ore.; Hazard, Ky.; Jefferson City, Mo.; Jonesboro, Ark.; Twin Falls, Idaho; and Wheeling, W.Va.