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Weather & Climate in Iroquois, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Iroquois experiences four distinct seasons with an average annual temperature of 51°F (10°C). Winters average 24°F in January while summers reach 74°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 38.4 inches. The area receives 17.1 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 665 feet.
Temperature
24°F Jan (-4°C)
74°F Jul (23°C)
| Annual Average | 50.7°F |
| 6% below US avg | |
| January Average | 24°F (-4°C) |
| July Average | 74°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 665 ft (203 m) |
| Area | 0.6 sq mi (1.6 km²) |
| Population Density | 360/sq mi |
| Coordinates | 40.8289°N, 87.5842°W |
| Timezone | America/Chicago |
| County | Newton County County |
| Nearest Airport | Vermilion Regional (DNV) 43 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 11.7 / 100 |
| Social Vulnerability | 25.3 / 100 |
| Community Resilience | 52.7 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Very Low |
| Winter Weather | Very Low |
| Lightning | Very Low |
| Ice Storm | Very Low |
| Drought | No Rating |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
9 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 | 131 km | 10 km |
| Jun 17, 2021 | Illinois-Indiana border region | M3.8 | 114 km | 6 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 148 km | 10 km |
| Apr 14, 2000 | 4 km NW of Heritage Lake, Indiana | M3.6 | 138 km | 5 km |
| Nov 4, 2013 | 1 km SSW of Lyons, Illinois | M3.2 | 110 km | 1 km |
| Dec 17, 1990 | Illinois-Indiana border region | M3.2 | 96 km | 10 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 131 km | 10 km |
| Dec 16, 1996 | 3 km NNE of Terre Haute, Indiana | M3.1 | 149 km | 5 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 82 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
631 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 71 fatalities, 1,372 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 26, 1994 | EF4 | 66 km | 14.0 mi | 3 |
| Jun 29, 1979 | EF4 | 94 km | 5.4 mi | 0 |
| Jun 13, 1976 | EF4 | 100 km | 3.3 mi | 2 |
| Mar 20, 1976 | EF4 | 63 km | 16.7 mi | 0 |
| Apr 3, 1974 | EF4 | 53 km | 108.7 mi | 18 |
| Apr 21, 1967 | EF4 | 96 km | 15.0 mi | 33 |
| Apr 11, 1965 | EF4 | 85 km | 21.8 mi | 0 |
| Apr 17, 1963 | EF4 | 58 km | 57.3 mi | 1 |
| Jun 22, 2015 | EF3 | 86 km | 16.3 mi | 0 |
| Nov 17, 2013 | EF3 | 82 km | 29.8 mi | 0 |
| Nov 17, 2013 | EF3 | 83 km | 37.9 mi | 0 |
| Jun 5, 2010 | EF3 | 30 km | 7.8 mi | 0 |
| Apr 19, 1996 | EF3 | 85 km | 2.0 mi | 1 |
| Mar 27, 1991 | EF3 | 94 km | 15.0 mi | 0 |
| Apr 2, 1982 | EF3 | 41 km | 12.0 mi | 0 |
| Jun 2, 1980 | EF3 | 94 km | 18.1 mi | 1 |
| Jun 25, 1978 | EF3 | 68 km | 27.4 mi | 0 |
| Mar 12, 1976 | EF3 | 21 km | 38.5 mi | 1 |
| Mar 12, 1976 | EF3 | 93 km | 12.1 mi | 0 |
| Jun 20, 1974 | EF3 | 52 km | 4.5 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Tsunami History
1 tsunami recorded within 500 km. Highest wave on record: 3.0 m (10 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1954 | MICHIGAN CITY, IN (LAKE MICHIGAN) | Avalanche | 3.0 m | 7 | 113 km |
Source: NOAA/NCEI Historical Tsunami Database.
Wildfire History
12 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (1,741 acres, 2019).
| Year | Name | Acres Burned | Distance |
| 2019 | UNNAMED | 1,741 | 78 km |
| 2019 | UNNAMED | 1,664 | 75 km |
| 2000 | UNNAMED | 1,602 | 18 km |
| 2021 | NORTHEAST PRAIRIE UNIT 3 | 978 | 71 km |
| 2024 | NORTHEAST PRAIRIE 3 RX | 938 | 72 km |
| 1986 | OGDEN DUNS | 863 | 92 km |
| 2021 | UNNAMED | 738 | 73 km |
| 2021 | MIDDLE GRANT CREEK | 700 | 77 km |
| 2019 | UNNAMED | 698 | 73 km |
| 2021 | 21-INDU TOLLESTON DUNES EAST | 594 | 92 km |
| 2017 | UNNAMED | 549 | 77 km |
| 2017 | 17 INDU COWLES DUNES | 522 | 99 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 24°F (-4°C) | 1.6 in | Coldest, Driest |
| February | 27°F (-3°C) | 1.6 in | |
| March | 38°F (4°C) | 3.0 in | |
| April | 50°F (10°C) | 3.8 in | |
| May | 61°F (16°C) | 4.1 in | |
| June | 70°F (21°C) | 4.1 in | Wettest |
| July | 74°F (23°C) | 4.1 in | Warmest |
| August | 72°F (22°C) | 3.7 in | |
| September | 65°F (18°C) | 3.4 in | |
| October | 53°F (12°C) | 2.8 in | |
| November | 41°F (5°C) | 3.1 in | |
| December | 29°F (-2°C) | 2.7 in |
Iroquois has a seasonal temperature swing of 50°F / from 24°F in January to 74°F in July. Total annual precipitation is 38.0 inches, with June being the wettest month (4.1") and January the driest (1.6").