Climate Matters•February 28, 2024
2024 Spring Package
KEY CONCEPTS
Meteorological spring starts March 1 and the season has warmed 2°F across the U.S. since 1970.
The spring season has warmed in 229 U.S. cities from 1970 to 2023 — by 2.2°F on average.
The Southwest has experienced the most spring warming, with locations in Nevada, Texas, and Arizona exceeding 6°F of spring warming since 1970.
Warm spring days now happen more often. About 73% of the 239 locations analyzed now have at least seven more warmer-than-normal spring days than they did in 1970.
In our warming world, spring-like conditions are arriving earlier — prolonging seasonal allergies, causing early snowmelt, and extending growing seasons.
Download data: Spring temperature trends
Download KML: Spring temperature trend map
Warming world, warming seasons
Like all other seasons, spring is getting warmer across the country. Since 1970, spring temperatures have increased by 2°F on average across the contiguous U.S.
These long-term warming trends largely reflect the warming caused by carbon pollution that traps excess heat in the atmosphere.
Climate Central analyzed spring average temperature data from 239 U.S. locations (see Methodology) to see how and where the spring season (March, April, May) has warmed from 1970 to 2023.
Spring is warming in 229 U.S. cities
Over the last 54 years, average spring temperatures have increased across the U.S.
Average spring temperatures increased in 229 (96%) of locations since 1970.
Over that period, the average spring warming across these 229 locations was 2.2°F.
Average spring temperatures warmed by 2°F or more in 129 (54%) of locations since 1970.
Spring warmed the most, on average, in locations across the southern tier of the country: Southwest (3.3°F), Southeast (2.4°F), and South (2.4°F).
The top spring warming locations were: Reno, Nev. (6.8°F); El Paso, Texas (6.3°F); Las Vegas, Nev. (6.2°F); Tucson, Ariz. (6°F); Phoenix, Ariz. (5.3°F); Albany, Ga. (5.3°F); and Chattanooga, Tenn. (5°F).
More warmer-than-normal spring days
The warming season is also reflected in the growing number of spring days above the 1991-2020 spring normal temperature for that location.
Since 1970, the average number of warmer-than-normal spring days has increased in 230 (96%) of the 239 locations analyzed.
The majority of locations (73%, or 175) now experience at least seven additional warmer-than-normal spring days than they did in 1970.
The rise in warmer-than-normal spring days was highest among locations in the Southwest (18 more days on average), West and Southeast (both 15 more days on average).
The cities with the largest increase in warmer-than-normal spring days since 1970 were: El Paso, Texas (38 more days); Reno, Nev. (37 more days); Tucson, Ariz. (36 more days); Tampa, Fla. (35 more days); and Albany, Ga. (33 more days).
Warmer springs affect health, water supplies, and agriculture
In the West, where spring warming is particularly pronounced, another critical resource is impacted: water. Warmer winters and springs mean less snow accumulation and earlier snowmelt, which stresses the region’s limited water resources.
Spring warming affects…
Western water supplies: Warming winters can reduce mountain snowpack. Warming springs can also contribute to earlier snowmelt, which stresses the region’s limited water resources. 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. The water deficit brought by earlier snowmelt has critical consequences for hydropower generation, agriculture, and drinking water supplies.
Seasonal allergies: Warmer, shorter winters mean earlier spring thaw and later fall freeze — giving plants more time to grow and release allergy-inducing pollen earlier in spring and later into fall. Data from the U.S. EPA shows that, over the last four decades (1980-2020), the last spring frost has arrived about three and a half days earlier than the long-term average (since 1985).
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.
Growing seasons and agriculture: 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. For example, a longer growing season might give some farmers the chance to diversify crops and find new markets. Other farmers might be faced with higher irrigation demands or more unwanted weeds and pests that can affect crop growth.
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.
LOCAL STORY ANGLES
When is spring blooming near you?
Check out the “springcasting” tools at USA National Phenology Network (USA-NPN), an organization of citizen scientists, government agencies, non-profit groups, and others, who monitor seasonal changes in the natural world. USA-NPN tracks the onset of spring across the country and has historical, real-time, and forecasted phenology maps. These are important tools for forecasting invasive species and pests, allergy outbreaks, and informing agricultural calendars.
How is allergy season in your area affected by warmer springs?
Check out how the duration of the pollen season has changed in your area since 1970 with Climate Central’s local graphics (available for 203 U.S. locations). Find out how your city ranked in the Asthma and Allergy Foundation of America report on the top 100 U.S. Allergy Capitals of 2022. Search for a local allergen report or sign up for pollen level alerts through the National Allergy Bureau.
Check out climate fingerprints on warm spring temperatures near you:
Climate Central’s Climate Shift Index (CSI) quantifies the influence of climate change on daily high and low temperatures experienced in cities across the U.S. To get notified about when CSI peaks in your area, sign up for our Realtime Climate alerts.
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 spring (March, April, May) from 1970 to 2023 using data obtained from the Applied Climate Information System. 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. However, for reported data summaries based on linear trends, only 239 stations are included due to data completeness measures that were not met by eight stations: Bend, Ore.; Dothan, Ala.; Hattiesburg, Miss., Hazard, Ky; Jefferson City, Mo.; Jonesboro, Ark.; Twin Falls, Idaho; and Wheeling, W.Va. Average spring warming since 1970 for U.S. climate divisions (displayed on the national map graphic in this release) use NCEI/NOAA Climate at a Glance data.