Dangerous wind chills, cold reach northern Illinois, expected through Tuesday: NWS

Dangerously cold wind chills, which could cause frostbite to exposed skin in under 30 minutes, are forecasted for most of northern Illinois from early Sunday until early Tuesday, according to the National Weather Service.

A cold weather advisory is in effect from 3 a.m. Sunday to noon Monday for much of the region, including parts of Winnebago, Boone, McHenry, Ogle, DeKalb and Kane counties. Wind chills could make temperatures feel as cold as 25 below zero.

Casey Sullivan, a meteorologist for the NWS Chicago office based in Romeoville, said those windchills, which measure how cold the air feels could be close to minus 30 degrees Tuesday morning.

“Wind chills during the afternoons will probably be 10 to 15 [degrees] below [zero], but it’s the nighttime and the morning hours when the wind chills will be the coldest,” Sullivan said. “It’s possible that the wind chills on Tuesday morning dip down into the [minus] 28 to minus 30 range for Tuesday morning.”

While Sullivan said Tuesday morning is forecasted to be the coldest morning of the week, it’s likely to earn that designation by only a few degrees.

After a strong cold front moved through the area Saturday, Sullivan said the area’s daily high temperatures will plummet by about 20 degrees for the first half of the week.

Temperatures for much of the region will only reach a high of 5 degrees on Sunday. Sullivan said the cold air isn’t expect to leave the area quickly. Temperatures will reach about 8 degrees Monday and 3 degrees Tuesday, he said.

Subzero low temperatures will drop to 5 below zero Monday morning, 9 below Tuesday morning and minus 4 degrees Wednesday morning.

Midweek is expected to bring a reprieve from the bitter cold.

“By Wednesday afternoon we’ll have high temperatures back in the lower 20s,” Sullivan said. “That time period through Wednesday morning, very cold conditions.”

This episode of arctic air isn’t quite a cold as what the area experienced between Jan. 14 and Jan. 17, 2024, according to the National Weather Service area forecast discussion.

Sullivan said Rockford, which was the closest location he had historical weather data for, said this week’s cold spell likely won’t come close to any records.

He said the record low in Rockford for Jan. 17 was 25 below in 1982. The record low for Jan. 8 is 23 below in 1994.

“We’re not anywhere close to record lows for this time of year in terms of the actual air temperature readings,” Sullivan said.