National Oceanic and Atmospheric Administration
Only one color was needed to show where July ranks in terms of hottest months on record.
"The average temperature for the contiguous U.S. during July was 77.6°F, 3.3°F above the 20th century average, marking the warmest July and all-time warmest month on record for the nation in a period of record that dates back to 1895. The previous warmest July for the nation was July 1936, when the average U.S. temperature was 77.4°F."
As NPR's Christopher Joyce has reported, "among scientists, there's a growing view that these latest heat waves are indeed a result of climate change."