[Editor’s Note: Our partner Climate Central has released data regarding temperature changes in the U.S. during the winter months from 1970 to 2021. Here are four important concepts regarding climate change and the winter season:]
- The winter season isn’t as cold as it used to be 50 years ago.
Using 52 years (1970-2021) of winter temperature data in 246 locations across the U.S, our analysis shows:
- About 98% (241) locations had an increase in their average winter temperatures since 1970, with 84% (202 of 241) of those locations warming by 2°F or more.
- Winter warming is greatest in the Great Lakes and Northeast region. The five greatest increases are seen in Burlington, Vt. (7.2°F), Concord, N.H. (6°F), Milwaukee (6°F), Chattanooga, Tenn. (5.8°F), and Green Bay, Wis. (5.8°F).
- About 74% (183) of the locations had at least 7 more days above the 1991-2020 winter normal temperatures since 1970.
- Since 1970, winter is the fastest-warming season for most of the U.S. All seasons are feeling the effect of climate change but a Climate Central analysis shows that, over the past 50 years, average temperatures increased more in winter than in any other season for 38 out of 49 states (excluding Hawaii).
- There can still be cold winters under climate change. The likelihood of extreme cold conditions in a warming world is decreasing but it is not zero. Some locations will still experience extreme cold or cold records—just not as cold or for as long as in the past.
- Although a majority of the U.S. has experienced an increase in winter temperatures, some northern states, including the Dakotas and Montana, have had colder winter temperatures since 1970.
- Some extreme cold spells occur when polar air spills south. Whether or how climate change may be linked with extreme winter weather in the mid-latitudes of the U.S., such as the February 2021 cold wave in Texas, is still an active area of research.
- Warming winters may sound great at first, but they can have negative impacts on our health and regional economies.
- Migrating pests: Disease-carrying insects such as mosquitoes and ticks can migrate to regions that were previously too cold to inhabit.
- Less snow and ice for winter sports: The multi-billion dollar winter recreation industry, which includes skiing, ice fishing, and snowmobiling, could take an economic hit because of rising temperatures and less snow/ice accumulation.
- Water supply risk: Warmer winters can lead to declining snowpacks in the West—a necessary source of meltwater that helps refill reservoir levels and irrigate crops in the spring.
- Lower fruit yields: Cherry, apple, and peach trees require a minimum number of winter chill hours before they can develop fruit in the subsequent spring and summer months. With the warming winter trends, this chill period is decreasing and could eventually limit fruit development.
Average temperatures and days above normal were calculated for each winter (December, January, February) from 1969-70 to 2020-21 using data obtained from the Applied Climate Information System. Winter days above normal are defined as the number of days where the average temperature was above the 1991-2020 NOAA/NCEI climate normal. Climate Central’s local analyses include 247 stations. However, for data summaries based on linear trends, only 246 stations are included due to large data gaps in Wheeling, W.Va.