News - The polar vortex brings a blast of cold air and early-season lake-effect snow. See maps.

A sharp drop in temperatures is moving into the eastern two-thirds of the country as a polar vortex dips down from the Arctic. Record cold high temperatures are expected on Monday and Tuesday across the South and Southeast along the Gulf Coast states. Heavy lake-effect snowfall is expected as the cold air interacts with the Great Lakes. The cold air, combined with a low-pressure system moving through the Northeast, is turning precipitation into snowfall in Michigan, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, and New York. Water temperatures in the Great Lakes are currently ranging from 40 to 50 degrees, which is relatively warmer than the cold air above them. The warmer waters are helping to enhance the moisture moving over them and are contributing to increased snow totals downwind of the lakes. Chicago issued its first Winter Storm Warning for the Chicago metropolitan area since January 12, 2024. That’s over 600 days since the last time winter weather conditions in the Chicago metro area warranted a Winter Storm Warning. As of 9 a.m. Monday, the Chicago metro area had seen 3.5 inches of snow, while Chicago Midway International Airport had recorded 2.5 inches. The highest snowfall totals so far have been in northwest Indiana, with some areas reporting over a foot. The Great Lakes will continue to experience winter weather conditions and accumulating snowfall through Tuesday and Wednesday. Polar vortex delivering chilly conditions: The polar vortex usually sits over the Arctic, but due to normal fluctuations in weather phenomena, it will sink into lower latitudes, which is what much of the U.S. is experiencing at the start of the week. It will shift back toward the pole after Wednesday. More than 90 million people were under Freeze Alerts from Texas to the Carolinas on Monday morning. The alerts will slowly expire as the cold shifts eastward. Wind chills are forecast to be as low as the teens, with sub-freezing overnight temperatures in the 20s and 30s. Temperatures are forecast to be 25-30 degrees below average for this time of year through Wednesday.