How many days a year do we have 100% of the possible sunshine in the Chicago area?

Dear Tom,
How many days a year do we have 100% of the possible sunshine in the Chicago area?
Linda Van, Lake Forest
Dear Linda,
Totally sunny days are a delightful, but fairly rare, commodity in Chicago, with the city’s long-term annual average at 45 days, according to Chicago climatologist Frank Wachowski.
February typically posts the fewest days with unlimited sunshine, averaging just less than three, while October provides the most, averaging 5.5.
Chicago’s longest string of totally sunny days is 10, from July 21-30, 1916, a month that delivered 95% of the possible sunshine with a record 24 totally sunny days.
The city’s all-time dreariest month was November 1985, which provided just 16% of possible sunshine.

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