High wind whipped up 10-foot waves and blew windows out of at least one building Wednesday in Chicago.
And forecasters warned the worst was yet to come.
The city closed its Lake Michigan jogging and cycling path and warned people to stay away in the face of predictions for 60-mph gusts and 25-foot waves.
Officials feared harsh weather could lead to a replay of the high waves that knocked down runners and bikers last month along the lakefront.
"Today's weather can cause serious injury if not taken seriously and the recommended precautions are ignored," emergency services director Gary Schenkel said in a statement reported by NBC station WMAQ.
Milwaukee, along Lake Michigan to Chicago's north, also expected high winds and waves.
Warnings for storm-forced winds extended to parts of Lake Huron into Thursday morning with forecasts for a lesser impact up into Lake Superior, the National Weather Service said.
By 7 a.m. CT, waves were splashing onto the lower portion of the path between North Avenue and Oak Street Beach in Chicago. A lakeshore flood warning was issued as a wind advisory warned of 40 to 45 mph winds with gusts to 60 mph, NBC station WMAQ reported.
In the afternoon, Wabash Avenue was closed to Pearson Street downtown because of glass falling from the 12th floor of a Loyola University building. A Morton Salt billboard visible from the Kennedy Expressway was reported down and blocking Elston Avenue, WMAQ reported.
"The high winds — we don't want anything to happen to anyone walking by, so as a precaution we're blocking off the street, the sidewalk and everything, just for personal safety," Chicago Fire Department Lt. David Bresnahan told WMAQ.
Flights were delayed at O'Hare International and Midway International airports, WMAQ said.
The Weather Channel reported that today's winds could be strong enough to topple trees and power lines, resulting in some potential power outages. The winds and up to one-and-a-half inches of rain could also cause hazardous road conditions, the forecast said.
Meteorologist Andy Avalos of WMAQ forecast that Wednesday night will be extremely windy, as well, with rain and lows between 43 and 48. Winds remain northerly at 40 to 45 mph.
Chicago should dry out Friday and Saturday with sunshine returning and temperatures leveling out by the weekend.