McHenry County Weather

09/01/2026

Heat (strong)
McHenry County

> 50% - Likely
Today 12:00 PM - 9:00 PM

Heat Advisory

* WHAT...Heat index values of 100 to 110 expected.

* WHERE...Boone, De Kalb, Lee, Ogle, Winnebago, Central Cook, DuPage, Kane, Lake IL, McHenry, and Northern Cook Counties.

* WHEN...From noon today to 9 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat illnesses.

* ADDITIONAL DETAILS...If showers and thunderstorms move across the area later this morning, the hot temperatures may not materialize.

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Consider altering outdoor plans.

NWS Chicago IL

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08/30/2026

Our daylight loss for September and it wouldn't matter if it was standard time or daylight savings time.

08/30/2026

Todays current SPC day 1 outlook:

08/30/2026

So, what does a very strong El-Nino mean for Northern, IL:

Seasonal Impacts for Northern Illinois

Summer (Rest Of) and Early Autumn: Conditions can lean slightly cooler and wetter than average as the pattern transitions, though overall global background warmth still applies.

Fall and Winter: Temperatures trend higher than usual (potentially averaging several degrees warmer), and precipitation—especially snow—decreases. Historic or "super" El Niño events have historically cut typical winter snowfall totals significantly.

Spring: Expect a tendency toward drier-than-average conditions as the event begins to weaken.

08/29/2026

I am loving the WeatherFront software on my phone and on browser on the desktop but I would love to see an actual windows program for it.

08/29/2026

New tornado record 🌪️ Illinois has had 243 preliminary tornado reports so far in 2026, exceeding the counts of any state for a full calendar year, dating back to 1950, according to Storm Prediction Center (SPC) data. https://bit.ly/4gxr3Pu

08/11/2026

Thunderstorm (severe)
Kane, IL; McHenry, IL

> 75% - Observed
Today 9:38 AM - 10:45 AM

Severe Thunderstorm Warning

The National Weather Service in Chicago has issued a

* Severe Thunderstorm Warning for... Kane County in northeastern Illinois... McHenry County in northeastern Illinois...

* Until 1045 AM CDT.

* At 937 AM CDT, severe thunderstorms were located along a line extending from near Machesney Park to near Cherry Valley to near Mendota, moving east at 50 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near... Marengo and Maple Park around 1000 AM CDT. Huntley, Hampshire, and Lily Lake around 1005 AM CDT. Elgin, Lake in the Hills, Woodstock, Campton Hills, Sugar Grove, Pingree Grove, Gilberts, and Elburn around 1010 AM CDT. Aurora, Crystal Lake, Carpentersville, St. Charles, Algonquin, Batavia, Geneva, South Elgin, Montgomery, and North Aurora around 1015 AM CDT. Bartlett, West Chicago, McHenry, Cary, Barrington Hills, Wonder Lake, East Dundee, Wayne, Valley View, and Prairie Grove around 1020 AM CDT. Island Lake, Fox River Grove, Oakwood Hills, and Port Barrington around 1025 AM CDT. Lakemoor around 1030 AM CDT.

Remain alert for a possible tornado! Tornadoes can develop quickly from severe thunderstorms. If you spot a tornado go at once into the basement or small central room in a sturdy structure.

Prepare immediately for damaging winds and deadly cloud to ground lightning. Seek shelter inside a well-built structure. Stay away from windows.

NWS Chicago IL

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08/11/2026

Thunderstorm (severe)
McHenry County

> 25% - Possible
Today 7:39 AM - 2:00 PM

Severe Thunderstorm Watch

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH 563 IN EFFECT UNTIL 2 PM CDT /3 PM EDT/ THIS AFTERNOON FOR THE

FOLLOWING AREAS

IN ILLINOIS THIS WATCH INCLUDES 18 COUNTIES

IN CENTRAL ILLINOIS

LIVINGSTON

IN EAST CENTRAL ILLINOIS

FORD IROQUOIS

IN NORTH CENTRAL ILLINOIS

BOONE DE KALB LA SALLE

LEE OGLE WINNEBAGO

IN NORTHEAST ILLINOIS

COOK DUPAGE GRUNDY

KANE KANKAKEE KENDALL

LAKE IL MCHENRY WILL

IN INDIANA THIS WATCH INCLUDES 5 COUNTIES

IN NORTHWEST INDIANA

BENTON JASPER LAKE IN

NEWTON PORTER

THIS INCLUDES THE CITIES OF ALGONQUIN, AURORA, BELVIDERE, BOLINGBROOK, BOURBONNAIS, BUFFALO GROVE, BYRON, CAROL STREAM, CHESTERTON, CHICAGO, COAL CITY, CRYSTAL LAKE, DEKALB, DEMOTTE, DIXON, DOWNERS GROVE, DWIGHT, ELGIN, EVANSTON, FAIRBURY, FOWLER, GARY, GIBSON CITY, GILMAN, GURNEE, HAMMOND, JOLIET, KANKAKEE, KENTLAND, LA SALLE, LEMONT, LOMBARD, MARSEILLES, MCHENRY, MENDOTA, MERRILLVILLE, MINOOKA, MOROCCO, MORRIS, MUNDELEIN, NAPERVILLE, OAK LAWN, OREGON, ORLAND PARK, OSWEGO, OTTAWA, OXFORD, PARK FOREST, PAXTON, PLANO, PONTIAC, PORTAGE, RENSSELAER, ROCHELLE, ROCKFORD, ROSELAWN, SCHAUMBURG, STREATOR, SYCAMORE, VALPARAISO, WATSEKA, WAUKEGAN, WHEATON, WILMINGTON, WOODSTOCK, AND YORKVILLE.

NWS Chicago IL

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08/10/2026

Severe Thunderstorm Watch is in effect for McHenry County, IL until 4:00 AM CDT.

More info:

WATCH COUNTY NOTIFICATION FOR WATCH 550 NATIONAL WEATHER SERVICE CHICAGO IL 844 PM CDT SUN AUG 9 2026 The National Weather Service has issued severe thunderstorm watch 550 in effect until 4 AM CDT /5 AM edt/ monday for the following areas in illinois this watch includes 18 counties in central illino...

08/09/2026

Thunderstorm (severe)
McHenry County

> 25% - Possible
Today 9:46 AM - 2:00 PM

Severe Thunderstorm Watch

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH 546 IN EFFECT UNTIL 2 PM CDT THIS AFTERNOON FOR THE FOLLOWING

AREAS

IN ILLINOIS THIS WATCH INCLUDES 2 COUNTIES

IN NORTHEAST ILLINOIS

LAKE IL MCHENRY

THIS INCLUDES THE CITIES OF ALGONQUIN, BUFFALO GROVE, CRYSTAL LAKE, GURNEE, MCHENRY, MUNDELEIN, WAUKEGAN, AND WOODSTOCK.

NWS Chicago IL

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