McHenry County, IL

Alerts

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Briefing

Last updated:

Monday, Jul 27, 2026, 5:19 AM

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From the Forecaster

Five Day Outlook

Created by the NWS Chicago WFO

Expect dangerously hot and humid conditions today with afternoon heat indices pushing 110°F or higher! Additionally, thunderstorms may develop during the PM hours, some of which may become strong or severe.

Image Description

This is a multiday forecast graphic for northern Illinois and northwest Indiana. Headline: Five Day Outlook. Sub Headline: Hot and humid today with some strong PM storms possible. Peak heat indices*. ~110°+ around and west of I-39. ~100° to locally 110° elsewhere in N IL and NW IN. Severe Storm Potential. Heat and Humidity Today. Storms may develop this afternoon and evening. *If storms develop, they may become severe with damaging winds and large hail. Visit weather.gov/Chicago for more forecast details for your location. Graphic Created: Monday, July 27, 2026 7:17 AM CDT

Chicago Area Forecast Discussion

Seven-day Weather Risk Overview

The graphic shows the daily risk summary for 7 days. Daily risk is based on highest risk factor for that day.

	Mon 7/27	Tue 7/28	Wed 7/29	Thu 7/30	Fri 7/31	Sat 8/1	Sun 8/2
risk level	out of 10				out of 10	out of 10

No risk

Low risk

High risk

See the detailed risk analysis

Radar

Time shown:

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dBz	Intensity
−35–0	Extremely light (drizzle/snow)
0–20	Very light precipitation or general clutter
20–40	Light precipitation
40–50	Moderate precipitation
50–65	Heavy precipitation or some hail
>65	Extremely heavy precipitation including water-coated hail

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Weather Forecasting Office

Chicago Forecast Office