Jan. 28–Severe winter weather in the Midwest is forcing Southwest and United airlines to either cancel, delay or divert some flights between San Diego and Chicago. Southwest says the disruption could last through Feb. 1.

Southwest canceled some flights between the two cities on Monday, and United delayed flights between 1 hour and more than 3 hours.

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Chicago was getting heavy snow on Monday morning. Conditions will deteriorate with the arrival of the polar vortex.

The National Weather Service says that the vortex could drop temperatures to minus-23 degrees on Tuesday night in Chicago, and to minus 21 degrees on Wednesday night. The temperature could plunge below minus-30 degrees in other parts of the Midwest. Forecasters say the wind chill could be minus 40 on Wednesday night in northern Illinois.

The cold weather will spread into the Northeast.

Southwest said that on Monday the weather also could affect major airports in Buffalo, Cleveland, Des Moines, Detroit, Grand Rapids, Milwaukee, Minneapolis-St. Paul and Rochester.

United Airlines has issued weather-related travel waivers for dozens of airports in the Midwest and Northeast due to the polar vortex. The airline said that such waivers enable travelers to change to alternate flights without paying a change fee. The changes can be made through Jan. 29.

The affected airports include, but aren’t limited to, Buffalo, New York-Kennedy, Cleveland, New York-Newark, Philadelphia, Ottawa and Quebec City. The fee will be in effect through Feb. 1 at Chicago-O’Hare.

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