CHICAGO (CBS)– As heavy snow hits the Chicago area Monday, airlines already have canceled over 300 flights at O’Hare and Midway international airports.

The Chicago area is under a Winter Storm Warning until Tuesday morning. The storm could bring as much as 8 to 12 or more inches of snow. Heaviest amounts of snow will be over the city and lakeshore, and then south and east of the city.

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As of 8:30 p.m. Monday, 234 flights had been canceled at O’Hare International Airport and average delays were less than 15 minutes.

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At Midway Airport, 155 flights have been canceled and average delays are less than 15 minutes.

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CHECK: U.S. Flight Delays | O’Hare Delays