Flights bound for Chicago's O'Hare International Airport are being delayed an average of nearly four hours because of dense fog.
The National Weather Service says fog and mist have reduced visibility at the airport to about 2 miles as a rainstorm moves through the area.
According to the flight tracking website FlightAware.com, flights scheduled to arrive at O'Hare are being delayed at their points of origin by an average of three hours and 49 minutes.
Around 170 flights to and from the airport have been canceled.
The tracking site is reporting no delays for inbound or outbound flights at Chicago's Midway International Airport.