June 11--It hit 90 degrees in the Chicago area Wednesday for the first time since last July, but then a stiff wind off the lake dropped temperatures 20 degrees along the lakefront within minutes.
The drastic temperature change comes as weather forecasters issued severe thunderstorm and flash flood warnings for the area.
Shortly before 3 p.m., it was 90 degrees at Northerly Island. By 4 p.m., it was 70.
The temperature drop was also noticeable at O'Hare International Airport, the city's official recording station. It went from 90 to 82 at 4 p.m.
The sudden change has made the air unstable and thunderstorms may develop rapidly over northern Illinois and northwest Indiana Wednesday evening, according to the National Weather Service.
Until the wind picked up, Wednesday was the warmest day in the Chicago area since July 22 of last year, the last time it hit 90. There were only two other 90-degree days last year: June 1 (90) and June 17 (91).
The warm air was driven by winds from the west and southwest. The winds shifted from the northwest in the middle of the afternoon, setting the stage for thunderstorms. Temperatures could drop to the upper 50s in some areas overnight.
Weather service officials issued a flash flood warning for the southwest side of Chicago, south of Midway Airport until 10:15 p.m. Wednesday. A severe thundestorm warning was also issued.
Thunderstorms are expected to continue through Friday, with highs in the mid-70s. It will remain cloudy Saturday and the high may not get out of the 60s. Rain is in the forecast through the early part of next week.
