People in the Northern Illinois area and a line of states north and south dragged out their coats after a spell of warm days was washed out by chilling rains.

Last week’s unseasonal high temperatures and pleasant weather—which stretched into the weekend—fell victim to colliding weather systems Saturday night and began pelting large areas of the Midwest with rain and sleet.

By 4 p.m. Sunday, about three-quarters of an inch had fallen in a rainy weather system extending from Southeastern Michigan through Illinois to Oklahoma, said Bob Sanderson, a forecaster for the National Weather Service in Rockford.

Sanderson said the sudden cold and wet is a result of a cold front from the North meeting with low pressure and warm air from the South. The two systems are interacting to make the dismal weather, which should be rain mixed with, or changing to, wet snow, he said.

Because temperatures were holding steady near the 32-degree freezing point Sunday, Sanderson said sleet was mixing in with the rain. And Sanderson, who said he expected Sunday night temperatures to dip below freezing, would not rule snow out of the forecast and said colder areas, including the Northern Illinois area, might see some accumulation of the white stuff.

However, the change during the weekend was not unusual, he said.

“It’s November,” Sanderson said. “We do get a change toward colder weather.”

Sanderson said October traditionally is a “change-over” month between the warmth of September and the chill of November and December. “It’ll get a whole lot colder” as the days creep toward December, he said.

But Sanderson said it’s not safe to say the area won’t get any more warm days until spring. “We have warm days until December,” he said.