Record warm start to Chicago winter to continue this week

It’s not you: So far this winter, Chicago has been abnormally warm.

Through Monday, the city’s temperatures are tied for Chicago’s fourth warmest start to the year. More incoming warm weather could push the record even higher, National Weather Service meteorologist Jake Petr said.

“It is certainly anomalously warm for this time of year,” Petr said.

The temperature reached 50 degrees at midnight Monday. The irregularity continued Tuesday, with a high of 41 degrees during the day amid drizzle in the northern suburbs and clouds.

The high mark is expected to reach into the 40s again on Wednesday and Thursday, with rain spread across the area Wednesday and potential snowfall near the Wisconsin-Illinois state line, Petr said.

So far this month, the average temperature in Chicago has been 36.6 degrees, a full 10.9 degrees above normal averages, he said.

“Quite noteworthy for sure,” Petr added. Rockford has seen similar record-setting warmth this month, he noted.

It’s too early to determine if the abnormally warm temperatures are related to global warming, the meteorologist said. However, one reason is the city’s snow pack has been kept down since melting in late December, meaning lingering snow and ice haven’t cooled temperatures, he said.

Petr said Chicago’s warmer conditions are occurring because of the current orientation of the upper jet stream, the same meteorological alignment affecting California with abnormally harsh weather.

But while the city is approaching what is typically the coldest time of the year — Jan. 23 claims the city’s coldest average temperature — sustained cold weather could still hit Chicago this winter.

Temperatures are expected to become more “seasonable” this weekend, with highs dropping into the mid-to low 30s.

“Certainly not cold as far as winter goes, but with what we’ve been used to so far this new year, it’ll feel a lot colder,” Petr said.

The Climate Prediction Center expects temperatures at the end of the month to have a roughly 50-50 chance of being below average, though it is hard to predict beyond that, he said. Neither a noteworthy cold stretch nor a noteworthy warm stretch are expected, he added.

And with half of January and the whole month of February left, snow at some point can’t be ruled out, Petr said.

“We’ve still got plenty of winter to go,” he said.

jsheridan@chicagotribune.com