CHICAGO (AP) — A significant portion of the United States braced for one of the initial bursts of winter weather this season on Sunday. As temperatures plummeted, snow graced the Northern Plains, while snowstorms began to spread eastward over the Great Lakes, and the South braced for an impending cold snap.

Light snowflakes fell over the Chicago area on Sunday, signaling the arrival of a more “intense” snowfall expected to commence in the evening around the Lake Michigan region. The National Weather Service issued a winter storm warning extending into Monday, forecasting wind gusts reaching up to 30 mph (48 kph) and snowfall possibly accumulating up to 18 inches (46 centimeters), accompanied by thundersnow, a phenomenon where thunderstorms occur with snow.

“This band will deliver very heavy snowfall and create challenging scenarios for the Monday morning commute,” stated Kevin Doom, a meteorologist with the weather service in Romeoville, Illinois.

Experts cautioned that driving conditions in northeastern Illinois could range from “dangerous to impossible” due to snow accumulating at rates exceeding 3 inches (8 centimeters) per hour.

As the cold gripped the nation’s central regions, meteorologists issued winter weather advisories across Michigan, Indiana, and Wisconsin, warning of hazardous travel conditions. Snow blanketed Michigan’s Upper Peninsula on Sunday, where forecasters predicted low visibility with up to a foot of snow by Monday. In Indiana, experts anticipated up to 11 inches (28 centimeters) of snow, cautioning drivers about “slippery surfaces.” Meanwhile, parts of Wisconsin were expected to receive up to 6 inches (15 centimeters) of snow.

“Patchy blowing snow” and wind chills hovering near zero were expected in portions of Minnesota, Nebraska and South Dakota. Some areas got measurable fluff a day earlier, including 4 inches (10 centimeters) of snow in southwest Minnesota and more than 5 inches (13 centimeters) in slices of northern Iowa.

Cold weather warnings were issued for Ohio, West Virginia and Kentucky, with freezing temperatures predicted through Monday morning for a large swath of the South, from Texas and Oklahoma to Alabama and Georgia.

Weather experts issued special guidance for gardeners, saying the freeze warning means the growing season has ended.

“Take steps now to protect tender plants from the cold,” warned meteorologists in Arkansas.