(ABC News) -- A pre-Christmas blizzard that is battering at least eight states in the middle of the nation could trip up travelers headed home for Christmas in the coming days.
Nearly 20 inches of snow have been reported in Colorado just west of Denver. Nebraska has reported 6-to-10 inches so far. Between 3 and 8 inches have accumulated in Iowa already and more is possible. Snow is falling 2 inches per hour in Wisconsin.
No planes were able to land at Iowa's Des Moines International airport. All flights were cancelled until at least 11:45 a.m.
But it's Chicago that will prove most problematic for travelers. Rain has cancelled 400 flights into and out of Chicago O'Hare today so far, according to data from FlightAware. Snow and wind that are expected tonight will further complicate travel and likely cancel more flights.
Southwest Airlines is cancelling all departures and arrivals at Midway Airport as of 4 p.m. local time. On a typical day the airline has between 200-220 flights in and out of Midway.
Southwest will also cancel all arrivals and departures from the Milwaukee Airport as of 6 p.m. local time. Southwest has 35 flights in and out of Milwaukee.
Several airlines have already issued flexible travel policies, allowing travelers with flights into, out of and through affected areas to change their plans without penalty. For example, travelers headed to O'Hare today on American Airlines can change their flight to any day Dec. 21 to Dec. 25. Delta, United and others have similar policies.
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