How many days in a year are Chicago’s temperatures at or above 70 degrees?

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Dear Tom,

We were recently at the Chicago Botanic Garden joying a 10,000 step fitness walk, bundled up against the sub-freezing temperatures when this came to my mind: How many days in a year are Chicago’s temperatures at or above 70 degrees? Those are ideal temperatures for an exercise walk.

Dominick Gatto

Dear Dominick,
We calculated the number of days per year with various temperature conditions. Of course, proximity to Lake Michigan affects temperatures. Near the lake, readings 70 or higher occur 118 days per year, but inland the number is greater: 145 days at Midway Airport and 140 at O’Hare. Readings in the 70s occur about 62 days at all three locations, but temperatures 80 or higher occur 55 days per year near the lake ranging to 86 days farther inland. Sub-freezing days: about 42 days at all locations.