Parts of northern Illinois and northwest Indiana will see the chance for severe thunderstorms over the next three days, with the biggest threat coming on Wednesday evening and into Thursday morning.
Before that, areas of far northern Illinois along the border with Wisconsin could see some strong thunderstorms on Tuesday night. The biggest threat with those storms will come in the form of gusty winds, with some exceeding 60 miles per hour, according to the National Weather Service.
Small hail is also possible with the storms.
A much larger portion of the state will be dealing with the threat of severe weather on Wednesday. In the late morning and early afternoon, isolated thunderstorms could potentially pop up, but the main event will come Wednesday evening, as more-defined lines of showers and thunderstorms are expected to drop from Wisconsin and sweep to the southeast, covering much of the Chicago metropolitan area.
In fact, most of northeastern Illinois, including the city of Chicago, will be classified under a “slight” risk of severe weather, according to the NOAA’s Storm Prediction Center. The far southwestern and southern portions of the NBC 5 viewing area, including LaSalle, Grundy and Kankakee counties, will be under a “marginal” risk of severe storms.
Those storms could pack heavy rains, which could lead to isolated flooding in some areas. Frequent lightning and gusty winds will also be expected with the storms, which could stick around the area until early Thursday morning.
In addition to the severe weather, the Chicago area will see stifling heat and humidity on Wednesday, with temperatures expected to climb into the mid-90s in some locations. Parts of the Chicago area could see heat indices soar above 100 degrees because of the humidity, posing hazards for those who are outdoors for long periods of time.
Thursday will still be humid and a bit cooler, with most of the threat of severe weather dropping south of Interstate 80 as a cold front finally pushes through the area.
The gusty winds will likely lead to hazardous swimming conditions on Lake Michigan, especially on the lake’s southern shores in northeast Illinois and northern Indiana. Those conditions will likely remain treacherous until at least Friday afternoon.
Temperatures will drop significantly by the end of the week, falling into the 70s or the low-80s in most locations. The highs will bump up slightly on Saturday, when another round of showers and thunderstorms could arrive in the area.