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Weather & Climate in Alton, IN
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Alton enjoys a temperate climate with an average annual temperature of 56°F (14°C). Winters average 33°F in January while summers reach 77°F in July. The area gets 290 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 51.0 inches (wetter than the 38-inch national average). Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 407 feet.
Temperature
33°F Jan (1°C)
77°F Jul (25°C)
| Annual Average | 56.3°F |
| 4% above US avg | |
| January Average | 33°F (1°C) |
| July Average | 77°F (25°C) |
| Sunny Days | 290 days/yr |
Geography
| Elevation | 407 ft (124 m) |
| Area | 0.2 sq mi (0.5 km²) |
| Population Density | 206/sq mi |
| Coordinates | 38.1201°N, 86.4186°W |
| Timezone | America/Indiana/Indianapolis |
| County | Perry County County |
| Nearest Airport | Louisville Muhammad Ali International (SDF) 37 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 35.0 / 100 |
| Social Vulnerability | 35.6 / 100 |
| Community Resilience | 67.9 / 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 Moderate |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
51 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 | 133 km | 14 km |
| Apr 18, 2008 | 9 km NNE of Bellmont, Illinois | M4.7 | 132 km | 15 km |
| Jun 18, 2002 | 6 km SW of Parkers Settlement, Indiana | M4.6 | 118 km | 16 km |
| Apr 21, 2008 | 7 km NNE of Bellmont, Illinois | M4.0 | 132 km | 18 km |
| Dec 7, 2000 | 7 km W of Evansville, Indiana | M3.9 | 108 km | 5 km |
| Jan 24, 1990 | 6 km WNW of Alton, Indiana | M3.9 | 7 km | 10 km |
| Jan 27, 1990 | 6 km N of Alton, Indiana | M3.8 | 7 km | 5 km |
| Sep 19, 2017 | 4 km N of Bellmont, Illinois | M3.8 | 135 km | 12 km |
| Nov 11, 1991 | 3 km W of Flat Rock, Illinois | M3.8 | 142 km | 0 km |
| Apr 25, 2008 | 8 km NNE of Bellmont, Illinois | M3.7 | 132 km | 13 km |
| Nov 20, 2012 | 7 km N of Bellmont, Illinois | M3.6 | 135 km | 19 km |
| Jun 5, 2008 | 8 km WNW of Mount Carmel, Illinois | M3.4 | 130 km | 16 km |
| May 1, 2008 | 8 km NNE of Bellmont, Illinois | M3.3 | 131 km | 14 km |
| May 10, 2012 | 0 km NW of Emison, Indiana | M3.1 | 119 km | 11 km |
| Jul 18, 2008 | 6 km NNE of Bellmont, Illinois | M3.1 | 134 km | 18 km |
| Sep 9, 2017 | 4 km N of Bellmont, Illinois | M3.1 | 135 km | 12 km |
| May 30, 2023 | 6 km W of Calhoun, Kentucky | M3.0 | 103 km | 0 km |
| Nov 28, 1998 | 6 km SW of Bremen, Kentucky | M2.9 | 116 km | 0 km |
| Jun 24, 2008 | 8 km NNE of Bellmont, Illinois | M2.9 | 131 km | 15 km |
| Jan 3, 2003 | 9 km SW of Mount Vernon, Indiana | M2.9 | 138 km | 2 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
495 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 81 fatalities, 1,316 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 3, 1974 | EF5 | 45 km | 32.0 mi | 31 |
| Apr 3, 1974 | EF5 | 30 km | 68.0 mi | 6 |
| Mar 2, 2012 | EF4 | 40 km | 45.1 mi | 11 |
| May 28, 1996 | EF4 | 59 km | 30.0 mi | 0 |
| Jun 2, 1990 | EF4 | 82 km | 18.0 mi | 0 |
| Jun 2, 1990 | EF4 | 74 km | 11.0 mi | 1 |
| Apr 3, 1974 | EF4 | 59 km | 18.5 mi | 3 |
| Apr 3, 1974 | EF4 | 79 km | 14.0 mi | 0 |
| Apr 3, 1974 | EF4 | 64 km | 37.9 mi | 3 |
| Apr 3, 1974 | EF4 | 75 km | 35.6 mi | 11 |
| May 25, 2011 | EF3 | 82 km | 6.8 mi | 0 |
| Mar 8, 2009 | EF3 | 83 km | 1.1 mi | 0 |
| Oct 18, 2007 | EF3 | 77 km | 7.0 mi | 0 |
| Oct 18, 2007 | EF3 | 85 km | 4.8 mi | 0 |
| Nov 15, 2005 | EF3 | 88 km | 12.0 mi | 0 |
| May 30, 2004 | EF3 | 27 km | 15.0 mi | 1 |
| May 23, 2000 | EF3 | 66 km | 6.0 mi | 0 |
| Jan 3, 2000 | EF3 | 80 km | 7.0 mi | 0 |
| Mar 28, 1997 | EF3 | 94 km | 9.0 mi | 1 |
| Mar 28, 1997 | EF3 | 95 km | 2.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
12 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (1,336 acres, 2017).
| Year | Name | Acres Burned | Distance |
| 2017 | UNNAMED | 1,336 | 15 km |
| 2019 | UNNAMED | 1,057 | 13 km |
| 2021 | UNNAMED | 959 | 12 km |
| 2014 | UNNAMED | 910 | 6 km |
| 2019 | UNNAMED | 892 | 6 km |
| 2024 | LONG RUN RX | 774 | 17 km |
| 2010 | FORK RIDGE RX | 697 | 99 km |
| 2010 | RICEVILLE RX | 671 | 30 km |
| 2019 | UNNAMED | 670 | 99 km |
| 2000 | UNNAMED | 641 | 90 km |
| 2019 | UNNAMED | 584 | 17 km |
| 2010 | ROCKHOUSE HOLLOW RX | 581 | 16 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 33°F (1°C) | 3.3 in | Coldest |
| February | 36°F (2°C) | 3.3 in | |
| March | 45°F (7°C) | 4.5 in | |
| April | 55°F (13°C) | 4.4 in | |
| May | 64°F (18°C) | 4.6 in | Wettest |
| June | 72°F (22°C) | 3.9 in | |
| July | 77°F (25°C) | 4.6 in | Warmest |
| August | 75°F (24°C) | 3.8 in | |
| September | 68°F (20°C) | 3.3 in | |
| October | 57°F (14°C) | 2.9 in | Driest |
| November | 46°F (8°C) | 3.9 in | |
| December | 37°F (3°C) | 3.8 in |
Alton has a seasonal temperature swing of 44°F / from 33°F in January to 77°F in July. Total annual precipitation is 46.2 inches, with May being the wettest month (4.6") and October the driest (2.9").