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Weather & Climate in Seymour, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Seymour experiences four distinct seasons with an average annual temperature of 51°F (11°C). Winters average 25°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 39.6 inches. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 700 feet.
Temperature
25°F Jan (-4°C)
73°F Jul (23°C)
| Annual Average | 51.1°F |
| 5% below US avg | |
| January Average | 25°F (-4°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 700 ft (213 m) |
| Area | 0.1 sq mi (0.2 km²) |
| Population Density | 3,700/sq mi |
| Coordinates | 40.1068°N, 88.4271°W |
| Timezone | America/Chicago |
| County | Piatt County County |
| Nearest Airport | Central Il Regional/Bloomington-Normal (BMI) 36 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 35.0 / 100 |
| Social Vulnerability | 24.6 / 100 |
| Community Resilience | 88.9 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Very Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
10 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.8.
| Jun 17, 2021 | Illinois-Indiana border region | M3.8 | 102 km | 6 km |
| Nov 11, 1991 | 3 km W of Flat Rock, Illinois | M3.8 | 147 km | 0 km |
| Apr 14, 2000 | 4 km NW of Heritage Lake, Indiana | M3.6 | 148 km | 5 km |
| May 13, 2025 | 7 km SSW of Lerna, Illinois | M3.3 | 84 km | 10 km |
| Jan 29, 1993 | 7 km WNW of Brownstown, Illinois | M3.2 | 130 km | 5 km |
| Dec 17, 1990 | Illinois-Indiana border region | M3.2 | 118 km | 10 km |
| Dec 16, 1996 | 3 km NNE of Terre Haute, Indiana | M3.1 | 111 km | 5 km |
| Sep 5, 2004 | 3 km WNW of Saint Peter, Illinois | M2.9 | 142 km | 33 km |
| Apr 24, 1990 | 5 km SW of Newton, Illinois | M2.9 | 130 km | 18 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 109 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
735 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 19 fatalities, 523 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 5, 1977 | EF4 | 72 km | 7.3 mi | 0 |
| Mar 20, 1976 | EF4 | 47 km | 63.7 mi | 0 |
| Nov 17, 2013 | EF3 | 26 km | 29.8 mi | 0 |
| Nov 17, 2013 | EF3 | 31 km | 18.7 mi | 0 |
| Aug 19, 2009 | EF3 | 98 km | 24.3 mi | 0 |
| Apr 19, 1996 | EF3 | 82 km | 9.4 mi | 0 |
| Apr 19, 1996 | EF3 | 72 km | 14.5 mi | 0 |
| Apr 19, 1996 | EF3 | 16 km | 4.0 mi | 0 |
| Apr 19, 1996 | EF3 | 41 km | 2.0 mi | 1 |
| Aug 21, 1977 | EF3 | 78 km | 26.9 mi | 6 |
| Aug 10, 1974 | EF3 | 65 km | 0.1 mi | 0 |
| Apr 3, 1974 | EF3 | 83 km | 25.9 mi | 0 |
| Apr 3, 1974 | EF3 | 22 km | 5.9 mi | 1 |
| Apr 3, 1974 | EF3 | 74 km | 20.9 mi | 1 |
| Apr 3, 1974 | EF3 | 49 km | 7.4 mi | 0 |
| Apr 3, 1974 | EF3 | 35 km | 14.9 mi | 0 |
| May 15, 1968 | EF3 | 84 km | 7.1 mi | 0 |
| Apr 22, 1963 | EF3 | 37 km | 38.6 mi | 0 |
| Apr 22, 1963 | EF3 | 33 km | 31.8 mi | 0 |
| Jul 21, 1961 | EF3 | 82 km | 23.9 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 25°F (-4°C) | 1.8 in | Coldest, Driest |
| February | 29°F (-2°C) | 1.8 in | |
| March | 40°F (5°C) | 3.2 in | |
| April | 52°F (11°C) | 3.9 in | |
| May | 63°F (17°C) | 4.2 in | |
| June | 72°F (22°C) | 3.8 in | |
| July | 73°F (23°C) | 4.5 in | Warmest, Wettest |
| August | 73°F (23°C) | 3.9 in | |
| September | 66°F (19°C) | 3.3 in | |
| October | 54°F (12°C) | 2.7 in | |
| November | 42°F (5°C) | 3.2 in | |
| December | 30°F (-1°C) | 2.9 in |
Seymour has a seasonal temperature swing of 48°F / from 25°F in January to 73°F in July. Total annual precipitation is 39.2 inches, with July being the wettest month (4.5") and January the driest (1.8").