Jun 12 | Climate Review and Weather Update
by Trent Ford, State Climatologist
ISWS PRI University of Illinois
We had a major swing in our weather this week, from warm and dry to hot and stormy. Average temperatures over the past 7 days ranged from the high 60s in northern Illinois to the high 70s in southern Illinois, between 3 and 10 degrees above average. However, the humidity was the noteworthy change this week, with dewpoints regularly reaching into the 60s and 70s, compared with the 40s in the first week of June. That humidity limited how much we could cool at night, resulting in several nights with low temperatures remaining in the 70s, including lows of 78 degrees in Carbondale and 76 in Charleston.
All that humidity fueled many rounds of storms and heavy precipitation, producing one of the more active weather weeks we’ve seen in some time in Illinois. 7-day rainfall totals ranged from less than half an inch in parts of southern Illinois to nearly 10 inches in some isolated parts of east-central and northern Illinois. Champaign-Urbana picked up nearly 3.5 inches this week, making it the wettest week here since November 2024. Unfortunately, the rain came with a lot of severe weather, including multiple large tornadoes, very strong straight line winds, and some hail. The NOAA Storm Prediction Center noted 12 tornado reports, 5 hail reports, and 160 severe wind reports in Illinois this week. Some of the notable storms included a very large and violent tornado that moved through parts of north-central Illinois, affecting multiple communities including Streator and Dwight. Strong wind was the primary hazard from this week’s storms, though, with many reports of wind gusts exceeding 70 mph, including 75 mph in Mason County, 78 mph in McLean County, and 82 mph in Iroquois County. As expected, the strong winds tore down trees, buildings, and power lines across northern and central Illinois. As of Friday morning, over 150,000 customers in northern Illinois and over 50,000 customers in central Illinois remained without power. Many of us will likely be greeted with the chorus of chain saws over the next few days as folks in Illinois start to clean up.
Looking ahead, I have mixed news. The not so great news is that we aren’t completely out of the severe weather yet. Saturday may bring another round of storms, with the highest risk of strong winds and isolated tornadoes especially in the western and southern parts of the state. However, once we get past Saturday night, our weather outlook turns much nicer. High temperatures will struggle to make it above 75 degrees statewide on Sunday and early next week, with much lower humidity. There may even be some isolated pockets of low temperatures in the upper 40s in northern Illinois on Monday morning.
Temperatures will increase a bit as we move into next weekend, but the week 2 outlooks from the Climate Prediction Center still show best chances of near to below normal temperatures. Despite the cooldown, next week we still be fairly wet. The 7-day precipitation forecast shows 1 to 2 inches for northern Illinois and up to 3 inches in southern Illinois.