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Weather & Climate in St. Peter, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St. Peter experiences four distinct seasons with an average annual temperature of 55°F (13°C). Winters average 29°F in January while summers reach 77°F in July. The area gets 293 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 41.2 inches. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 592 feet.
Temperature
29°F Jan (-2°C)
77°F Jul (25°C)
| Annual Average | 54.6°F |
| 1% above US avg | |
| January Average | 29°F (-2°C) |
| July Average | 77°F (25°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 592 ft (180 m) |
| Area | 0.2 sq mi (0.5 km²) |
| Population Density | 492/sq mi |
| Coordinates | 38.8676°N, 88.8504°W |
| Timezone | America/Chicago |
| County | Marion County County |
| Nearest Airport | St Louis Regional (ALN) 64 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 77.1 / 100 |
| Social Vulnerability | 68.6 / 100 |
| Community Resilience | 96.5 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Relatively Moderate |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Low |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
60 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.2.
| Apr 18, 2008 | 7 km NNE of Bellmont, Illinois | M5.2 | 96 km | 14 km |
| Apr 18, 2008 | 9 km NNE of Bellmont, Illinois | M4.7 | 97 km | 15 km |
| Jun 18, 2002 | 6 km SW of Parkers Settlement, Indiana | M4.6 | 136 km | 16 km |
| Apr 21, 2008 | 7 km NNE of Bellmont, Illinois | M4.0 | 97 km | 18 km |
| Dec 7, 2000 | 7 km W of Evansville, Indiana | M3.9 | 145 km | 5 km |
| Sep 19, 2017 | 4 km N of Bellmont, Illinois | M3.8 | 95 km | 12 km |
| Nov 11, 1991 | 3 km W of Flat Rock, Illinois | M3.8 | 99 km | 0 km |
| Apr 25, 2008 | 8 km NNE of Bellmont, Illinois | M3.7 | 97 km | 13 km |
| Jan 2, 2006 | 3 km NNE of Eldorado, Illinois | M3.6 | 120 km | 7 km |
| Nov 20, 2012 | 7 km N of Bellmont, Illinois | M3.6 | 94 km | 19 km |
| Mar 2, 1990 | 9 km NW of Vernon, Illinois | M3.4 | 28 km | 0 km |
| May 30, 2015 | 4 km ENE of Geff, Illinois | M3.4 | 62 km | 26 km |
| Jun 5, 2008 | 8 km WNW of Mount Carmel, Illinois | M3.4 | 99 km | 16 km |
| May 1, 2008 | 8 km NNE of Bellmont, Illinois | M3.3 | 98 km | 14 km |
| May 13, 2025 | 7 km SSW of Lerna, Illinois | M3.3 | 71 km | 10 km |
| Apr 6, 1994 | 2 km NE of Tamaroa, Illinois | M3.2 | 85 km | 15 km |
| Jan 29, 1993 | 7 km WNW of Brownstown, Illinois | M3.2 | 24 km | 5 km |
| Oct 24, 1990 | 5 km ENE of Woodlawn, Illinois | M3.2 | 59 km | 1 km |
| May 2, 2003 | 10 km ENE of Thompsonville, Illinois | M3.2 | 102 km | 0 km |
| Jul 1, 2017 | 9 km SSE of Mulberry Grove, Illinois | M3.1 | 33 km | 17 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
511 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 32 fatalities, 453 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Dec 18, 1957 | EF5 | 94 km | 5.4 mi | 1 |
| Nov 17, 2013 | EF4 | 72 km | 10.6 mi | 2 |
| Jun 2, 1990 | EF4 | 51 km | 12.5 mi | 0 |
| Jun 2, 1990 | EF4 | 47 km | 23.0 mi | 0 |
| Jun 2, 1990 | EF4 | 76 km | 106.0 mi | 1 |
| Dec 18, 1957 | EF4 | 68 km | 16.8 mi | 1 |
| Mar 31, 2023 | EF3 | 69 km | 40.9 mi | 6 |
| Dec 1, 2018 | EF3 | 77 km | 12.5 mi | 0 |
| Apr 21, 2002 | EF3 | 59 km | 31.5 mi | 1 |
| Jun 1, 1999 | EF3 | 87 km | 10.0 mi | 1 |
| Apr 19, 1996 | EF3 | 80 km | 17.0 mi | 0 |
| Dec 2, 1982 | EF3 | 83 km | 10.5 mi | 2 |
| Aug 21, 1977 | EF3 | 65 km | 26.9 mi | 6 |
| Jul 28, 1976 | EF3 | 71 km | 0.1 mi | 0 |
| Mar 20, 1976 | EF3 | 94 km | 8.8 mi | 0 |
| Aug 10, 1974 | EF3 | 95 km | 0.1 mi | 0 |
| Aug 10, 1974 | EF3 | 52 km | 0.1 mi | 0 |
| Apr 3, 1974 | EF3 | 98 km | 20.9 mi | 1 |
| Apr 1, 1974 | EF3 | 99 km | 3.3 mi | 0 |
| Mar 6, 1961 | EF3 | 38 km | 21.2 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 29°F (-2°C) | 2.1 in | Coldest, Driest |
| February | 32°F (-0°C) | 2.2 in | |
| March | 43°F (6°C) | 3.9 in | |
| April | 54°F (12°C) | 3.8 in | |
| May | 64°F (18°C) | 4.2 in | Wettest |
| June | 73°F (23°C) | 4.1 in | |
| July | 77°F (25°C) | 3.9 in | Warmest |
| August | 75°F (24°C) | 3.0 in | |
| September | 68°F (20°C) | 3.1 in | |
| October | 56°F (14°C) | 2.9 in | |
| November | 44°F (7°C) | 3.7 in | |
| December | 33°F (1°C) | 3.4 in |
St. Peter has a seasonal temperature swing of 48°F / from 29°F in January to 77°F in July. Total annual precipitation is 40.1 inches, with May being the wettest month (4.2") and January the driest (2.1").