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Weather & Climate in Lacon, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Lacon experiences four distinct seasons with an average annual temperature of 53°F (11°C). Winters average 26°F in January while summers reach 76°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 24.6 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 510 feet.
Temperature
26°F Jan (-3°C)
76°F Jul (24°C)
| Annual Average | 52.6°F |
| 3% below US avg | |
| January Average | 26°F (-3°C) |
| July Average | 76°F (24°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 510 ft (155 m) |
| Area | 1.6 sq mi (4.2 km²) |
| Population Density | 1,078/sq mi |
| Coordinates | 41.0229°N, 89.4063°W |
| Timezone | America/Chicago |
| County | Marshall County County |
| Nearest Airport | Illinois Valley Regional-Walter A Duncan Field (VYS) 26 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 27.2 / 100 |
| Social Vulnerability | 45.7 / 100 |
| Community Resilience | 92.1 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Very Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Very Low |
| Winter Weather | Very Low |
| Lightning | Very Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
6 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 | 65 km | 10 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 130 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 78 km | 5 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 90 km | 10 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 131 km | 5 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 76 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
680 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 27 fatalities, 656 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 9, 2015 | EF4 | 93 km | 30.1 mi | 2 |
| Nov 17, 2013 | EF4 | 47 km | 46.4 mi | 3 |
| Jul 13, 2004 | EF4 | 26 km | 9.6 mi | 0 |
| Mar 29, 1981 | EF4 | 86 km | 5.1 mi | 0 |
| May 5, 1977 | EF4 | 87 km | 7.3 mi | 0 |
| Jun 29, 1976 | EF4 | 38 km | 4.9 mi | 0 |
| Feb 28, 2017 | EF3 | 51 km | 11.5 mi | 2 |
| Feb 28, 2017 | EF3 | 13 km | 17.8 mi | 0 |
| Jun 22, 2015 | EF3 | 91 km | 16.3 mi | 0 |
| Jun 5, 2010 | EF3 | 57 km | 8.6 mi | 0 |
| Apr 20, 2004 | EF3 | 27 km | 15.8 mi | 8 |
| May 10, 2003 | EF3 | 66 km | 17.5 mi | 0 |
| Apr 19, 1996 | EF3 | 78 km | 9.4 mi | 0 |
| May 13, 1995 | EF3 | 80 km | 25.0 mi | 0 |
| May 9, 1995 | EF3 | 45 km | 22.0 mi | 0 |
| Mar 13, 1990 | EF3 | 97 km | 15.5 mi | 0 |
| Jun 30, 1977 | EF3 | 71 km | 6.1 mi | 0 |
| Mar 4, 1976 | EF3 | 24 km | 0.8 mi | 0 |
| Jul 23, 1975 | EF3 | 94 km | 11.1 mi | 0 |
| Jul 23, 1975 | EF3 | 82 km | 14.0 mi | 2 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 26°F (-3°C) | 1.5 in | Coldest |
| February | 27°F (-3°C) | 1.3 in | Driest |
| March | 39°F (4°C) | 2.8 in | |
| April | 50°F (10°C) | 3.7 in | |
| May | 61°F (16°C) | 3.9 in | |
| June | 71°F (21°C) | 4.0 in | Wettest |
| July | 76°F (24°C) | 3.9 in | Warmest |
| August | 73°F (23°C) | 3.6 in | |
| September | 65°F (18°C) | 3.9 in | |
| October | 54°F (12°C) | 2.7 in | |
| November | 40°F (5°C) | 2.7 in | |
| December | 28°F (-2°C) | 2.2 in |
Lacon has a seasonal temperature swing of 50°F / from 26°F in January to 76°F in July. Total annual precipitation is 36.2 inches, with June being the wettest month (4.0") and February the driest (1.3").