Weather & Climate in Thorntown, IN
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Thorntown experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 26°F in January while summers reach 74°F in July. Annual precipitation totals 42.1 inches. The area receives 18.1 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 36. 87% of days have good air quality. The city sits at an elevation of 857 feet.
Temperature
26°F Jan (-3°C)
74°F Jul (23°C)
| Annual Average | 51.7°F |
| 4% below US avg | |
| January Average | 26°F (-3°C) |
| July Average | 74°F (23°C) |
Geography
| Elevation | 857 ft (261 m) |
| Area | 0.6 sq mi (1.6 km²) |
| Population Density | 1,893/sq mi |
| Coordinates | 40.1292°N, 86.6100°W |
| Timezone | America/Indiana/Indianapolis |
| County | Boone County County |
| Nearest Airport | Indianapolis International (IND) 33 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 36.0 |
| Rating | Good |
| Good Days % | 87.2% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 43.2 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 98.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Moderate |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Very 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: M3.8.
| Jun 17, 2021 | Illinois-Indiana border region | M3.8 | 67 km | 6 km |
| Sep 12, 2004 | 4 km NW of Manilla, Indiana | M3.8 | 100 km | 2 km |
| Dec 20, 1990 | 5 km S of Stilesville, Indiana | M3.7 | 60 km | 5 km |
| Apr 14, 2000 | 4 km NW of Heritage Lake, Indiana | M3.6 | 43 km | 5 km |
| Dec 17, 1990 | Illinois-Indiana border region | M3.2 | 38 km | 10 km |
| Dec 16, 1996 | 3 km NNE of Terre Haute, Indiana | M3.1 | 97 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
614 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 88 fatalities, 1,956 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 11, 1998 | EF4 | 68 km | 13.2 mi | 0 |
| Apr 26, 1994 | EF4 | 49 km | 14.0 mi | 3 |
| Mar 20, 1976 | EF4 | 50 km | 16.7 mi | 0 |
| Apr 3, 1974 | EF4 | 60 km | 108.7 mi | 18 |
| Apr 3, 1974 | EF4 | 92 km | 18.9 mi | 0 |
| May 14, 1972 | EF4 | 60 km | 30.0 mi | 0 |
| Apr 11, 1965 | EF4 | 25 km | 45.7 mi | 28 |
| Apr 11, 1965 | EF4 | 36 km | 48.0 mi | 25 |
| Apr 11, 1965 | EF4 | 29 km | 21.8 mi | 0 |
| Apr 25, 1961 | EF4 | 92 km | 63.1 mi | 0 |
| Mar 31, 2023 | EF3 | 95 km | 6.4 mi | 0 |
| Mar 31, 2023 | EF3 | 93 km | 5.9 mi | 2 |
| Mar 31, 2023 | EF3 | 79 km | 5.5 mi | 0 |
| Aug 24, 2016 | EF3 | 51 km | 8.6 mi | 0 |
| Nov 17, 2013 | EF3 | 31 km | 37.9 mi | 0 |
| Jun 5, 2010 | EF3 | 67 km | 7.5 mi | 0 |
| May 30, 2004 | EF3 | 78 km | 4.5 mi | 0 |
| Sep 20, 2002 | EF3 | 100 km | 112.0 mi | 0 |
| Jun 11, 1998 | EF3 | 55 km | 18.5 mi | 0 |
| Nov 22, 1992 | EF3 | 81 km | 15.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 26°F (-3°C) | 2.7 in | Coldest |
| February | 30°F (-1°C) | 2.5 in | Driest |
| March | 40°F (5°C) | 3.1 in | |
| April | 52°F (11°C) | 4.3 in | |
| May | 62°F (17°C) | 4.4 in | |
| June | 71°F (22°C) | 4.7 in | Wettest |
| July | 74°F (23°C) | 4.6 in | Warmest |
| August | 72°F (22°C) | 3.5 in | |
| September | 66°F (19°C) | 3.1 in | |
| October | 54°F (12°C) | 3.0 in | |
| November | 42°F (5°C) | 3.4 in | |
| December | 31°F (-0°C) | 2.8 in |
Thorntown has a seasonal temperature swing of 47°F / from 26°F in January to 74°F in July. Total annual precipitation is 42.1 inches, with June being the wettest month (4.7") and February the driest (2.5").