McHenry County weather, town by town
40 places in McHenry County, Illinois, each with its own live forecast and radar, and where a station sits close enough, measured weather records.
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Measured at the NOAA stations serving these towns, daily records 1897 to 2026. Station extremes, not official state records.
McHenry County Weather Facts
McHenry County has 40 places on myweatherrock (22 villages, 13 census-designated places, 5 cities), each with its own live forecast, hourly timeline, ten day outlook and radar. The hottest day in the station records is 106°F at Lake Geneva Wwtp on August 1, 1988. The coldest night is -32°F at Mchenry Stratton Lock/Dam on January 31, 2019. The wettest day brought 5.72 inches of rain at Barrington 3Sw on July 23, 2011. The biggest single-day snow measured 21.1 inches at Woodstock 5Nw on February 2, 2011. Those are station measurements from NOAA's daily records, 1897 to 2026, not official state records. By area the largest place is Crystal Lake, about 19 square miles.
About McHenry County weather
The map on the Now tab shows every McHenry County town's current temperature from our own server, one dot per town. Tap any dot, or type a town above, for that town's full forecast.
What the weather is usually like
Across the 40 McHenry County towns with station normals, the warmest month is July, when the day usually reaches 83°F, and the coldest is January, when the night usually falls to 13°F. May is the wettest, with rain on about 13 days. July afternoons run from about 82°F in Chemung to 85°F in Alden. January nights run from about 11°F in Chemung to 15°F in Alden.
Means of the 1991 to 2020 station normals serving these towns, as published by NOAA; each town's page carries its own.
Where these numbers come from
- Current conditions and forecast: NOAA forecast grids decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
- Records: computed by myweatherrock from NOAA GHCN-Daily station records at the stations serving these towns. Measurements, not estimates.
- Warnings and alerts: the National Weather Service, passed through unchanged.
McHenry County weather records
Measured at the NOAA stations serving these towns, daily records 1897 to 2026. Station extremes, not official state records.
Common questions about McHenry County weather
- What is the hottest temperature recorded at a McHenry County station?
- 106°F at Lake Geneva Wwtp on August 1, 1988, in the NOAA daily station records myweatherrock holds (1897 to 2026).
- What is the coldest temperature recorded at a McHenry County station?
- -32°F at Mchenry Stratton Lock/Dam on January 31, 2019.
- What is the most rain a McHenry County station has measured in one day?
- 5.72 inches at Barrington 3Sw on July 23, 2011.
- What is the biggest one-day snowfall at a McHenry County station?
- 21.1 inches at Woodstock 5Nw on February 2, 2011.
- How many McHenry County towns have a weather page here?
- 40: 22 villages, 13 census-designated places, 5 cities. Each page carries current conditions, the hourly timeline, the ten day outlook, radar, and where a station sits close enough, measured records.
- Where does the McHenry County forecast come from?
- NOAA forecast grids (the National Weather Service digital forecast, the National Blend of Models, HRRR and GFS) decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
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