CHICAGO (CBS) — A line of severe thunderstorms hit the Chicago area Monday, causing power outages, flight cancellations and delays and other problems. By late Monday, a second wave of storms was expected.

A tornado warning was issued for Southwest Cook County and Northwest Will County late Monday.

The storm systems that came in from the west around 5 p.m. brought high winds, rain and lightning. At one point, a ground stop was issued for planes arriving at O’Hare Airport, where hundreds of flights were canceled. Both O’Hare and Midway experienced delays of up to two hours.

The White Sox-Angels game was washed out at U.S. Cellular Field (a doubleheader was scheduled for Tuesday with the Los Angeles Angels), and 23,000 customers of ComEd were without power across the Chicago region. Flooding was a concern for some areas.

West suburban Aurora clocked winds of 61 mph – tropical storm force – said CBS 2 Meteorologist Steve Baskerville, who predicted a second wave of storms to sweep through the area late Monday.

On the positive side, the storms were expected to cool off the hot and muggy conditions the Chicago area has seen the past few days, with temperatures dropping to the low 70s overnight.

After Tuesday, the high temperature might not get above 80 degrees the rest of the week, with a high of only about 73 on Tuesday, and lows in the low 60s or upper 50s each night this week.