Crozet Weather Almanac: June 2018

Courtesy Roscoe Shaw and Heidi Sonen.

Summer Heat… Count the Days

June finished a touch warmer than normal and July started off scorching hot with the dreaded combination of heat and humidity.  But before you whine too much, remember that you live in the South and it is summer.  What do you expect?

Many people believe that our summers are hotter than they used to be but that is not really the case.  Overall, the earth has definitely warmed in the last few decades but almost all of the warming has happened at night, in the winter, and in the north.  “Global warming” should really be called “global less cold” but that’s not very catchy.

Ironically, the lack of hotter “hot days” combined with warmer low temperatures is exactly what the atmospheric physics suggest in an atmosphere with more carbon dioxide.  This provides empirical evidence that carbon dioxide is a key driver of rising global temperature.

A look at the data shows that we average eight days a year where the temperature hits 95 or more.  The hottest decade was the 1930’s when 134 days hit 95 or more.  The dust bowl years of the 1930s still hold the most records for hot temperatures in the USA.

The decade with the fewest hot days was the 1970s with just 34 days reaching 95 degrees.  Overall, there is no trend toward hotter summer afternoons.

One thing not included in the data is humidity.  Overall, moisture has increased slightly in recent decades although it is difficult to quantify. Humidity is difficult to measure correctly, and older records are poor.

The bottom line is that summers are hot in central Virginia, but it was just as bad for your grandparents, maybe worse. 


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