Mercer County weather, town by town
16 places in Mercer 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 1895 to 2026. Station extremes, not official state records.
Mercer County Weather Facts
Mercer County has 16 places on myweatherrock (7 villages, 6 census-designated places, 3 cities), each with its own live forecast, hourly timeline, ten day outlook and radar. The hottest day in the station records is 113°F at Aledo on July 15, 1936. The coldest night is -33°F at Aledo on January 30, 2019. The wettest day brought 7.47 inches of rain at New Boston Dam 17 on August 17, 1939. The biggest single-day snow measured 20 inches at Illinois City Dam 16 on February 2, 2011. Those are station measurements from NOAA's daily records, 1895 to 2026, not official state records. By area the largest place is Keithsburg, about 3 square miles.
About Mercer County weather
The map on the Now tab shows every Mercer 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 16 Mercer County towns with station normals, the warmest month is July, when the day usually reaches 85°F, and the coldest is January, when the night usually falls to 14°F. May is the wettest, with rain on about 12 days. January nights run from about 13°F in Aledo to 16°F in Eliza.
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.
Mercer County weather records
Measured at the NOAA stations serving these towns, daily records 1895 to 2026. Station extremes, not official state records.
Common questions about Mercer County weather
- What is the hottest temperature recorded at a Mercer County station?
- 113°F at Aledo on July 15, 1936, in the NOAA daily station records myweatherrock holds (1895 to 2026).
- What is the coldest temperature recorded at a Mercer County station?
- -33°F at Aledo on January 30, 2019.
- What is the most rain a Mercer County station has measured in one day?
- 7.47 inches at New Boston Dam 17 on August 17, 1939.
- What is the biggest one-day snowfall at a Mercer County station?
- 20 inches at Illinois City Dam 16 on February 2, 2011.
- How many Mercer County towns have a weather page here?
- 16: 7 villages, 6 census-designated places, 3 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 Mercer 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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