Northern Illinois is staring down another blast of bitter Arctic air later this week, capping off what has already been one of the most aggressive starts to winter in decades.

After a brief warmup Tuesday into early Wednesday, with temperatures temporarily climbing above freezing, a strong clipper system will sweep across the Midwest and open the door to a much sharper and longer-lasting push of cold air.

Forecasters expect temperatures to tumble through the latter half of the week, with single-digit lows looking increasingly likely across much of the region this weekend. Some areas could even dip below zero.

Wind chills will be the bigger story. As a surge of northwesterly winds follows an arctic front late week, “feels-like” temperatures may plunge toward minus 20 at times, especially during the overnight and early morning hours.

The National Weather Service warns that the pattern of fast-moving disturbances will keep winds elevated and the cold firmly entrenched through at least Sunday.

The incoming cold comes as the Chicago area already is off to a remarkable start to the snow season. O’Hare has recorded 17.1 inches so far, the quickest start since 1978, and nearly as much as fell during the entire 2024–25 winter. Rockford is keeping pace with 17.1 inches of its own, marking the fastest start since reliable records began in 1905.

Before the deep freeze sets in, Tuesday night into Wednesday will bring a round of rainfall as temperatures briefly reach the 30s and lower 40s. As colder air races back in on Wednesday, rain may flip to snow, though accumulation is uncertain due to limited moisture.

The bottom line for the end of the week: prepare for the coldest air of the season so far, and potentially the harshest stretch northern Illinois has seen in several years.