After a semi-white Christmas, snow possible overnight Sunday before warmup begins; temps could be above freezing by end of week

Temperatures in the Chicago area are forecast to reach a balmy 22 degrees Monday, but first slightly more snow is expected to fall.

After days of below zero temperatures and dangerously cold windchills, the area was beginning to warm up Christmas Day. Windchills remained in the negative double-digits Sunday morning, but the temperature was expected to rise to about 14 degrees, or more than 20 degrees warmer than during some of the coldest periods in the days before. Wind gusts were slowing, said Brian Leatherwood, a meteorologist with the National Weather Service of Chicago.

“It’s a relative improvement, but it’s still bad out there,” he said. “People still need to be cautious, dress warmly, wear layers and try to minimize the exposure of skin.”

Hundreds of flights at O’Hare International and Midway airports were canceled as temperatures plummeted and winds picked up Thursday and Friday — just as scores of people were trying to reach holiday destinations — but by Sunday morning the cancelations had fallen into the dozens. At 9:30 a.m., 71 flights scheduled for Sunday at O’Hare had been canceled, and 65 had been canceled at Midway, according to the website FlightAware.

Up to an inch of snow could fall across the Chicago area Sunday night and Monday morning, most of it before morning commuting hours. Because temperatures have been so cold, the snow will accumulate and could make roads slick, especially where they are untreated or less traveled, Leatherwood said.

Temperatures could reach a high of 22 degrees Monday, and into the upper 20s Tuesday, Leatherwood said. After that, winds from the south could blow much warmer air into the Chicago area, raising temperatures into the 40s, he said.

Some parts of the region could approach 50 degrees by the end of the week, which would mean they could feel more than 80 degrees warmer than they did when windchills were close to -35, Leatherwood said.

After a frigid Christmas weekend well below average temperatures, New Year’s weekend is expected to be warm and rainy.

sfreishtat@chicagotribune.com