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Weather & Climate in Deer Grove, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Deer Grove experiences four distinct seasons with an average annual temperature of 49°F (10°C). Winters average 21°F in January while summers reach 73°F in July. The area gets 275 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 36.8 inches. The area receives 35.9 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 647 feet.
Temperature
21°F Jan (-6°C)
73°F Jul (23°C)
| Annual Average | 49.3°F |
| 9% below US avg | |
| January Average | 21°F (-6°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 647 ft (197 m) |
| Area | 0.5 sq mi (1.2 km²) |
| Population Density | 80/sq mi |
| Coordinates | 41.6097°N, 89.6866°W |
| Timezone | America/Chicago |
| County | Whiteside County County |
| Nearest Airport | Illinois Valley Regional-Walter A Duncan Field (VYS) 33 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 65.8 / 100 |
| Social Vulnerability | 43.6 / 100 |
| Community Resilience | 81.7 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Moderate |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Low |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
7 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.2.
| Jun 28, 2004 | 12 km NW of Dayton, Illinois | M4.2 | 68 km | 10 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 106 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 24 km | 5 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 81 km | 10 km |
| Mar 25, 2015 | 3 km WNW of Lake in the Hills, Illinois | M2.9 | 127 km | 6 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 106 km | 5 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 115 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
618 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 41 fatalities, 737 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 9, 2015 | EF4 | 43 km | 30.1 mi | 2 |
| Jul 13, 2004 | EF4 | 95 km | 9.6 mi | 0 |
| Mar 29, 1981 | EF4 | 23 km | 5.1 mi | 0 |
| Jun 29, 1976 | EF4 | 90 km | 4.9 mi | 0 |
| Apr 21, 1967 | EF4 | 93 km | 25.5 mi | 24 |
| Feb 28, 2017 | EF3 | 82 km | 17.8 mi | 0 |
| Feb 28, 2017 | EF3 | 69 km | 11.5 mi | 2 |
| Jun 5, 2010 | EF3 | 98 km | 8.6 mi | 0 |
| Apr 20, 2004 | EF3 | 52 km | 15.8 mi | 8 |
| May 9, 1995 | EF3 | 36 km | 22.0 mi | 0 |
| May 9, 1995 | EF3 | 99 km | 10.0 mi | 0 |
| Mar 13, 1990 | EF3 | 49 km | 15.5 mi | 0 |
| May 8, 1988 | EF3 | 92 km | 32.0 mi | 0 |
| Aug 5, 1979 | EF3 | 47 km | 5.7 mi | 0 |
| Aug 15, 1978 | EF3 | 99 km | 6.4 mi | 0 |
| Jun 30, 1977 | EF3 | 57 km | 6.1 mi | 0 |
| Mar 4, 1976 | EF3 | 47 km | 0.8 mi | 0 |
| Jun 20, 1974 | EF3 | 64 km | 10.6 mi | 1 |
| Jun 14, 1974 | EF3 | 86 km | 48.6 mi | 0 |
| May 13, 1974 | EF3 | 76 km | 3.6 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 21°F (-6°C) | 1.4 in | Coldest |
| February | 25°F (-4°C) | 1.3 in | Driest |
| March | 37°F (3°C) | 2.6 in | |
| April | 49°F (10°C) | 3.7 in | |
| May | 61°F (16°C) | 4.4 in | |
| June | 70°F (21°C) | 4.6 in | Wettest |
| July | 73°F (23°C) | 3.7 in | Warmest |
| August | 72°F (22°C) | 4.4 in | |
| September | 64°F (18°C) | 3.5 in | |
| October | 53°F (11°C) | 2.8 in | |
| November | 38°F (4°C) | 2.6 in | |
| December | 26°F (-3°C) | 2.1 in |
Deer Grove has a seasonal temperature swing of 52°F / from 21°F in January to 73°F in July. Total annual precipitation is 37.1 inches, with June being the wettest month (4.6") and February the driest (1.3").