Weather Alerts For Winnebago, IL

# HEADLINE -------------------- HEAT ADVISORY IN EFFECT UNTIL 10 PM CDT THIS EVENING # DETAILS -------------------- WHAT Peak heat index values this afternoon of 100 to locally 110 degrees. WHERE Portions of north central and northeast Illinois and northwest Indiana. WHEN Until 10 PM CDT this evening. IMPACTS Hot temperatures and high humidity may cause heat illnesses. ISSUED AT Friday, September 4, 2026 at 2:54 AM CDT ISSUED BY National Weather Service Chicago IL HEADER URGENT - WEATHER MESSAGE # PRECAUTIONARY/PREPAREDNESS ACTIONS -------------------- Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. # AREAS AFFECTED -------------------- Kendall, Southern Will, Boone, Central Cook, De Kalb, DuPage, Eastern Will, Kane, Lake IL, Lake IN, Lee, McHenry, Northern Cook, Northern Will, Ogle, Porter, Southern Cook, Winnebago Including the cities of Oak Lawn, Sycamore, Channahon, Mundelein, Elgin, McHenry, Joliet, Yorkville, Lemont, Oak Park, Downers Grove, Chicago, Schaumburg, Portage, Algonquin, Park Forest, Dixon, Merrillville, Mokena, Palatine, Gary, Plano, Oak Forest, Hammond, Oregon, Valparaiso, Calumet City, Evanston, Oswego, Rockford, Byron, Orland Park, Gurnee, Bolingbrook, Beecher, Buffalo Grove, Des Plaines, La Grange, Wilmington, DeKalb, Manhattan, Rochelle, Plainfield, Lombard, Crystal Lake, Belvidere, Cicero, Waukegan, Peotone, Carol Stream, Chesterton, Crete, Naperville, Woodstock, Wheaton, Northbrook, and Aurora

There is a Marginal Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING ACROSS PART OF THE MID ATLANTIC INTO MIDDLE OHIO VALLEY...AND ACROSS PARTS OF THE UPPER MIDWEST SUMMARY Scattered strong thunderstorm development, posing mainly a risk for severe wind and hail, remains possible into the overnight hours across parts of the Mid Atlantic and Upper Midwest into the Great Lakes. Mid Atlantic A convectively generated or augmented mid-level perturbation continues to migrate east-southeastward across the upper Ohio Valley, toward the northern Mid Atlantic, along the southern fringe of broadly cyclonic flow overspreading the Northeast. This continues to provide support for a clustering of stronger convective development currently in a corridor across east central Ohio into south central Pennsylvania. Although this activity appears to have waned some in intensity from earlier, updraft inflow emanating from a more moist environment, along and south of a diffuse remnant outflow boundary across the central Maryland through Delmarva Peninsula vicinity, might reinvigorate activity later this evening into the overnight hours. Upper Midwest into Great Lakes region Convective evolution into and through the overnight hours remains a bit unclear. An initial cluster of convection, supported by a short wave impulse now progressing toward the Minnesota/Ontario border vicinity and Lake Superior, is undergoing substantial weakening as inflow becomes more stable to the cool side of a quasi-stationary frontal zone, which roughly extends from the Red River Valley through southern Great Lakes region. Upstream, near the crest of building mid/upper ridging, lower/mid-tropospheric warm advection is supporting scattered renewed thunderstorm development across northwestern and west central Minnesota. Closer to the frontal zone, where the inflow environment is characterized by moderate to strong instability, there still appears potential for the evolution of a small organizing cluster across the Brainerd MN vicinity through mid to late evening. As this progresses eastward, it is not clear that this will be maintained overnight. A strengthening southwesterly low-level jet may focus additional upscale growing thunderstorm development downstream, across parts of northeastern Wisconsin into Lower Michigan, but, elevated to the cool side of the frontal zone, it is not clear that the environment will support more than very limited potential for severe hail and wind.

Pollen Index: 10.2 Pollen Level: high Predominant Pollen: Ragweed, Chenopods and Grass. Pollen concentrations for Friday will be greater than today's levels and extend further into the very high range. This higher level is caused in part by higher temperatures and the lower dewpoint.