Do we have more cloudy days during the winter months?

Dear Tom,

Do we have more cloudy days during the winter months or does it just seem that way?

Suzanne M. Maack

Dear Suzanne,

Winter, with its persistent and extensive cloudiness is most definitely Chicago’s cloudiest season. Chicago climatologist Frank Wachowski, who painstakingly documents Chicago sunshine, reports that, on average, the city’s cloudiest months are all in late fall and winter. December, typically the year’s cloudiest month averages 41 percent of possible sun, followed by November and January with 42 percent and 47 percent in February. Contrast that to the typical 68 percent of possible sun in July, the city’s sunniest month. Citing sunshine data back to late 1893, Wachowski noted that the city’s all-time dreariest month was November, 1985 with just 16 percent of possible sun, compared to 95 percent in July 1916 the city’s sunniest month.