Does the number of sunny days in the Chicago area vary by season? For example, is winter seasonally more sunny than fall or spring?
Anna Lange Chicago
It certainly does. Chicago weather historian Frank Wachowski has been documenting Chicago’s sunshine since the 1950s and provided this information. Based on percent of possible sunshine, summer into early autumn is Chicago’s sunniest period, led by July averaging 68 percent, followed by June with 65 percent and August and September with 64 percent. December is the cloudiest month averaging 41 percent, closely followed by November and January with 42 percent. Based on totally sunny days (100 percent sunshine), October leads all months with 626 days followed by September with 518. In contrast, the months with the least sunny days are February with 327 and December with 334.