This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Dear Tom,
Thinking about solar energy, I’m wondering what percent of potential sunlight the Chicago area gets in a typical year. Can you help?

Al Glueckert Skokie

Dear Al,
We sure can. Annually, Chicago receives about 54 percent of its possible sunshine. Chicago climatologist Frank Wachowski has been measuring the city’s sunshine since the 1950s, sustaining a database dating back to September 1893. Not surprisingly, summer is the city’s sunniest time of the year, with the normal percent of possible sunshine in excess of 60 percent from June through September. July tends to be the sunniest month, typically logging 68 percent of the possible sun. Winter, is a decidedly different, dreary story with normal sunshine averaging just above 40 percent from November through January. The spring and fall transition seasons generally score sunshine values between 49-57 per cent.