Wettest Seasons in U.S. Regions

Climate Central analyzed precipitation data from 1969-70 to 2022-23 for the contiguous U.S., finding that while some regions have balanced seasonal rainfall, others rely heavily on a single season. Specifically, the West and Northwest are dominated by winter precipitation, while the Plains and Upper Midwest rely on summer rainfall. Climate change is altering these patterns, with a general increase in precipitation east of the Rockies and a decrease to the west. Warmer temperatures are increasing atmospheric moisture—approximately 10% more since 1970—which enhances extremes such as heavy downpours and intensifying droughts.

• Regional precipitation patterns in the contiguous U.S. vary significantly: the West and Northwest are primarily dependent on winter precipitation, whereas the Plains, Upper Midwest, and parts of the Southwest rely more on summer precipitation.
• Long-term trends since 1901 show an overall increase in U.S. precipitation, though this is regionally split; increases occurred in the Northeast, Midwest, Great Plains, Ohio Valley, and South, while decreases were seen in the West and Southwest.
• A comparison of normal periods from 1981-2010 and 1991-2020 indicates that annual average precipitation has increased east of the Rockies and decreased to the west, particularly in the Southwestern U.S.
• Fourteen U.S. states receive at least one-third of their annual precipitation in a single season, with nine states receiving 40% or more in one season, increasing their vulnerability to climate-driven precipitation shifts. For example, California receives 52% of its precipitation in winter, while North Dakota receives 45% in summer.
• Atmospheric moisture capacity increases by 4% for every 1°F of warming. Because the U.S. has warmed by 2.6°F since 1970, the atmosphere now holds approximately 10% more moisture on average, increasing the risk of heavy rainfall and flooding.

APA

Climate Central (2023). Wettest Seasons in U.S. Regions. https://www.climatecentral.org/climate-matters/wettest-seasons-in-us-regions-2023

Chicago

Climate Central. Wettest Seasons in U.S. Regions. 2023. https://www.climatecentral.org/climate-matters/wettest-seasons-in-us-regions-2023.

Wikipedia

{{cite report |author=Climate Central |title=Wettest Seasons in U.S. Regions |date=18 October 2023 |url=https://www.climatecentral.org/climate-matters/wettest-seasons-in-us-regions-2023 |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{climatecentral2023wettest, author = {{Climate Central}}, title = {{Wettest Seasons in U.S. Regions}}, institution = {Climate Central}, year = {2023}, month = oct, url = {https://www.climatecentral.org/climate-matters/wettest-seasons-in-us-regions-2023}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }