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Weather & Climate in Mercer, WI
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Mercer has a cool climate with an average annual temperature of 40°F (5°C). Winters average 11°F in January while summers reach 66°F in July. The area gets 253 sunny days per year, above the national average. Air quality is rated Good with a median AQI of 38. The city sits at an elevation of 1,598 feet.
Temperature
11°F Jan (-12°C)
66°F Jul (19°C)
| Annual Average | 40.2°F |
| 26% below US avg | |
| January Average | 11°F (-12°C) |
| July Average | 66°F (19°C) |
| Sunny Days | 253 days/yr |
Geography
| Elevation | 1,598 ft (487 m) |
| Area | 5.5 sq mi (14.2 km²) |
| Population Density | 121/sq mi |
| Coordinates | 46.1613°N, 90.0418°W |
| Timezone | America/Chicago |
| County | Iron County County |
| Nearest Airport | Rice Lake Regional/Carl's Field (RIE) 98 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 38.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 11.5 / 100 |
| Social Vulnerability | 76.1 / 100 |
| Community Resilience | 31.6 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Hurricane | No Rating |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Low |
| Ice Storm | Very Low |
| Drought | Very Low |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
| Coastal Flood | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
1 earthquake (M2.5+) recorded within 150 km since 1990. Strongest on record: M2.5.
| Jan 7, 2024 | 3 km NE of Mole Lake, Wisconsin | M2.5 | 112 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
106 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 5 fatalities, 72 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 25, 1950 | EF4 | 74 km | 13.1 mi | 2 |
| Jun 8, 1985 | EF3 | 42 km | 68.0 mi | 2 |
| Apr 27, 1984 | EF3 | 57 km | 29.0 mi | 1 |
| Jul 7, 1970 | EF3 | 11 km | 37.9 mi | 0 |
| May 3, 1955 | EF3 | 96 km | 6.8 mi | 0 |
| Jul 27, 2010 | EF2 | 46 km | 0.9 mi | 0 |
| Sep 30, 2002 | EF2 | 78 km | 3.0 mi | 0 |
| Apr 26, 1994 | EF2 | 88 km | 12.0 mi | 0 |
| Jun 27, 1991 | EF2 | 43 km | 6.0 mi | 0 |
| Jul 4, 1986 | EF2 | 58 km | 1.5 mi | 0 |
| Jun 13, 1981 | EF2 | 78 km | 0.1 mi | 0 |
| Sep 20, 1972 | EF2 | 63 km | 13.1 mi | 0 |
| Jun 26, 1969 | EF2 | 27 km | 28.9 mi | 0 |
| Aug 14, 1961 | EF2 | 41 km | 4.5 mi | 0 |
| Jul 14, 1958 | EF2 | 2 km | 1.5 mi | 0 |
| Jun 25, 1950 | EF2 | 69 km | 8.4 mi | 0 |
| Aug 9, 2020 | EF1 | 46 km | 6.2 mi | 0 |
| Aug 9, 2020 | EF1 | 57 km | 5.9 mi | 0 |
| Jul 18, 2020 | EF1 | 74 km | 0.6 mi | 0 |
| Jul 11, 2016 | EF1 | 24 km | 2.3 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Wildfire History
5 wildfires (100+ acres) recorded within 100 km. Largest: RILEY (1,254 acres, 2019).
| Year | Name | Acres Burned | Distance |
| 2019 | RILEY | 1,254 | 38 km |
| 2007 | PIONEER FIRE | 1,072 | 88 km |
| 1987 | FOULDS CREEK | 750 | 37 km |
| 2022 | UNNAMED | 702 | 37 km |
| 2022 | LDF MARSH BURN 2022 | 503 | 15 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 11°F (-12°C) | 1.4 in | Coldest |
| February | 15°F (-10°C) | 1.0 in | Driest |
| March | 25°F (-4°C) | 1.8 in | |
| April | 39°F (4°C) | 2.3 in | |
| May | 52°F (11°C) | 3.7 in | |
| June | 61°F (16°C) | 4.0 in | |
| July | 66°F (19°C) | 3.9 in | Warmest |
| August | 64°F (18°C) | 4.3 in | Wettest |
| September | 55°F (13°C) | 4.1 in | |
| October | 44°F (7°C) | 2.9 in | |
| November | 29°F (-2°C) | 2.2 in | |
| December | 16°F (-9°C) | 1.7 in |
Mercer has a seasonal temperature swing of 55°F / from 11°F in January to 66°F in July. Total annual precipitation is 33.1 inches, with August being the wettest month (4.3") and February the driest (1.0").