This FILE photo shows smog on the shoreline of Chicago during a summer heat wave. (iStock/NOAA)PHILADELPHIA - Summer 2021 was the hottest on record for the contiguous United States, slightly surpassing the Dust Bowl summer of 1936 by less than 0.01 degrees Fahrenheit, according to a report released Thursday by NOAA.The average temperature during climatological summer – June through August – for the Lower 48 states was 74 degrees, or 2.6 degrees above the 20th-century average.
A record 18.4% of the contiguous U.S. endured record-high temperatures for the season.California, Idaho, Nevada, Oregon and Utah each reported their hottest June-to-August period on record, and 16 additional states recorded one of their five hottest summers on record..