The Chicago area’s third 80° high of the year turned out to be elusive Wednesday thanks to thunderstorms which flared to the west and dissipated before reaching the city. But before that happened, their towering clouds, dubbed cumulonimbus by meteorologists, managed to mix cold air from the upper reaches of the storms down to earth’s surface producing what amounted to a natural air-conditioning effect. Wednesday’s surge in temperatures—which had reached 76° at Northerly Island by midday—halted when the storms’ rain-cooled outflow and leftover debris clouds cut into the supply of warming sunlight.
Even so, readings officially peaked at 73° at both O’Hare and Midway, marking the 14th time this year the mercury’s exceeded 70°. Nine such occurrences have been the average here since 1871—and only 11 had occurred by this time a year ago.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
