Nine states across the U.S. have been issued with winter weather warnings by the National Weather Service (NWS), with some expected to see up to 18 inches of snowfall from Sunday through to Tuesday morning.

A cold weather advisory in North Texas warns of a wind chill of 10 degrees or lower. The wind chill represents the “feels like” temperature in an area, which is calculated using the air temperature and the wind speed.

For central Cook County including Chicago, the Winter Storm Warning was downgraded to a Winter Weather Advisory around 5 a.m. But elsewhere in Cook County, the Winter Storm Warning remains in effect.