New climate 'Normals' show warming across much of US, NOAA says

Climate Normals, which help us better understand today's weather and make smarter decisions related to climate, have been updated, the National Oceanic and Atmospheric Administration said Tuesday. Not surprisingly, average annual temperature changes in the US indicate a "warming pattern" happening in much of the country, NOAA said. 

Annual US precipitation changes also showed drier conditions in the southwest, and wetter sections in the Northern Plains, Great Lakes region and southeast. NOAA compared 1981-2010 Climate Normals to the latest data in the 1991-2020 Normals to reach those findings.

"An upward shift in temperature averages is evident, but warming is not ubiquitous across the contiguous U.S. in either geographic space or time of year," NOAA said in a statement. "Changes vary from season-to-season and month-to-month."

These new US Normals are a way for the public, weather forecasters and businesses to compare conditions today to 30-year averages, NOAA said. They're ideal for getting a better idea of what's happening now, by seeing the impact the changing climate has on day-to-day weather. 

Changes in averages "can be subtle, depending on the region, season, and timeframe," according to NOAA, but there are still some clear differences based on the most recent data. 

"For instance, the north-central U.S. Temperature Normals -- for those in the Northern Plains and Upper Midwest -- have cooled from 1981-2010 to 1991-2020, especially in the spring," the administration said. "The South and Southwest are considerably warmer. Normals were also generally warmer across the West and along the East Coast."

These Normals are more than just averages of raw data, NOAA said. It involves gathering 30 years of US weather station observations, checking for quality, comparing to nearby stations and adding missing periods. 

"These then provide a basis for comparisons of temperature, precipitation, and other variables to today's observations," the administration said. 

Members of the World Meteorological Organization have to calculate their country's Normals every 10 years, as part of something that's "the equivalent of the Census for those who use the data," NOAA said. These Normals offer data about national and local average temperature and precipitation, in addition to other measurements like snowfall and frost and freeze dates. People can use this information to determine if a variable at a certain location, such as temperature, is above, below or near average.