Feb 21 | Climate Review and Weather Forecast
Finally, the coldest week of the year by far has come to an end. Average temperatures this week ranged from the single digits in northwest Illinois to the high 20s in southern Illinois, between 10 and 20 degrees below normal. Nighttime low temperatures regularly dipped into the single digits to well below zero, including -15 in McHenry and -12 in Freeport. Even Carbondale briefly dipped below zero this week. Maybe more impressive was the fact that several places did not get above freezing the entire week. Elgin’s highest temperature since last weekend was 27 degrees.
Not much changed in the position of the jet stream, meaning precipitation this week mostly stayed south of Interstate 70. 7-day totals ranged from less than a tenth of an inch in western Illinois to over 4 inches in far southern Illinois. This week reinforced a large gradient in precipitation that goes back to the beginning of the year. Much of central Illinois has had less than 50% of normal precipitation since January 1st, while parts of the south-seven counties have seen over 150% of normal precipitation this year so far. Some of the precipitation in southern Illinois this week came in snow form, continuing what has been a very snowy winter for the southern third of the state. 7-day snowfall totals were as high as 7 inches in southeast Illinois. Fairfield has had nearly 25 inches of snowfall so far this season, about 10 inches above normal for the entire season and the 8th most on record there. Meanwhile, Chicago has only had about 15 inches of the white stuff so far this season, the lowest total since 2013.
Looking ahead, temperatures thankfully begin to climb today and through this weekend. Highs will reach into the 30s and 40s statewide on Saturday and Sunday, and the St. Louis area may see the 60s early next week. Nighttime low temperatures will stay above freezing for most of the state next week, which after this week, will feel like a heatwave. Precipitation will be limited next week, with totals less than half an inch statewide. Farther out, the first week of March is looking slightly wetter and cooler than normal, but it’s important to remember that temperatures normally begin to climb as February turns to March, so even cooler than normal will be milder than what we had this week. The first outlooks for the entire month of March show best chances of a wetter than normal start to spring, with near normal temperatures.