NOAA released the new 30-year running average on July 1, which incorporates data from the period 1981-2010 to replace the 1971-2000 observations used to determine normal temperatures.
“The climate of the 2000s is about 1.5 degrees Fahrenheit warmer than the 1970s, so we would expect the updated 30-year normals to be warmer,” said Thomas R. Karl, National Climatic Data Center director.
Florida and Missouri experienced the least amount of increase in maximum temperatures, while the Great Lakes, Rockies and Desert Southwest had the greatest amount of daytime warming.
But the biggest change was seen in minimum overnight temperatures, which warmed much more than the afternoon highs of the past 30 years.
NOAA points out that there was a great deal of variability in the amount of climate change experienced across the nation.
Florida and other parts of the southeastern U.S. actually had somewhat cooler overnight temperatures during January over the past three decades.