August 21st used to be a hot day in the US, but maximum temperatures have declined since the 19th century.
On August 21, 1936, 21 percent of US stations were over 100°F, compared to two percent last year (NASA’s hottest year ever™).
About half of the Eastern US was over 100°F on August 21, 1936.
August 21, 1983, was the hottest day on record in North Carolina. Fayetteville was 110 degrees F.
NOAA doesn’t like the fact that August afternoon temperatures in the US are declining, so they simply alter the data in a hockey stick to hide the decline.
Read more at Real Climate Science