A powerful winter storm barreling through the Midwest sent Chicago’s airports into chaos Saturday, with more than 600 flights wiped out at O’Hare before the heaviest snow even arrived.

O’Hare logged 627 cancellations by 9:45 a.m., along with 331 delays, according to FlightAware.

The Chicago Department of Aviation said delays were averaging 37 minutes as fliers packed terminals trying to escape the mess.

The Federal Aviation Administration issued a ground delay at O’Hare that stretched to roughly five hours.

A brief ground stop earlier in the morning had been lifted by 9:45 a.m.

Midway fared better but still saw major disruptions.

The airport reported 76 cancellations by 9:50 a.m. and delays under 15 minutes.

That amounted to 29% of flights canceled at Midway and 46% at O’Hare.

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