The chilly winds which greet Chicagoans Thursday are doing what April winds have done over the years nearly half (42%) the time here—blowing from the east. March, April and May mark the heart of Chicago’s so-called lake wind season—a period in which “cooler by the lake” is a refrain all too often included in area forecasts.
These east winds come off chilly Lake Michigan. The lake’s waters warm frustratingly slowly. That’s because water exhibits a property engineers refer to as thermal inertia—the tendency of a substance to pretty well maintain a given temperature for a protracted period even as warming occurs around it.
Wednesday’s high marked the 10th time in April daytime temps have failed to break above 50°. That had happened only two times during the same period a year ago. Though chilly here, temps soared to the west—reaching 74° at Williston and 71° at Bismarck, both in North Dakota.
--By Tom Skilling, WGN-TV Chief Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
