evidence: Climate change highlights the need for regularly updating these normals. For the past 10 years, weather professionals have used the 1981-2010 climate normals as our reference. But we’ve observed above-average temperatures much more frequently than below-average temperatures from 1991-2020 for much of the U.S. Updating the normals is a way to calibrate to our most recently observed climate. [...] Across the continental U.S., the temperature rose by about 0.5 F on average from the 1981-2010 to 1991-2020 period. The new average is 1.2 F warmer than that of the 20th century. A couple of exceptions are cooling observed in the spring over the Northern Great Plains and cooling over the Southeast and Mid-Atlantic in November. December shows the greatest amount of warming.