WASHINGTON (AP) - Record heat returned to the United States with a vengeance in May.
Federal meteorologists calculate that May warmed to a record 65.4 degrees in the Lower 48 states, breaking a record set in 1934.
Last month, the average temperature across the Lower 48 states was 5 degrees warmer than normal.
It was especially record-warm at night during May. The National Oceanic and Atmospheric Administration reported Wednesday that the average overnight low temperature broke the record by 2 degrees.
NOAA climate scientist Jake Crouch says the high heat comes after a cool April.
Scientists said climate change played a role along with other factors.
U.S. temperature records go back to 1895.