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Weather & Climate in Fort Thompson, SD
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Fort Thompson experiences four distinct seasons with an average annual temperature of 47°F (8°C). Winters average 18°F in January while summers reach 74°F in July. The area gets 276 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 20.1 inches (drier than the 38-inch national average). The area receives 18.9 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 35. The city sits at an elevation of 1,437 feet.
Temperature
18°F Jan (-8°C)
74°F Jul (24°C)
| Annual Average | 46.7°F |
| 14% below US avg | |
| January Average | 18°F (-8°C) |
| July Average | 74°F (24°C) |
| Sunny Days | 276 days/yr |
Geography
| Elevation | 1,437 ft (438 m) |
| Area | 12.6 sq mi (32.6 km²) |
| Population Density | 109/sq mi |
| Coordinates | 44.0549°N, 99.4048°W |
| Timezone | America/Chicago |
| County | Buffalo County County |
| Nearest Airport | Pierre Regional (PIR) 49 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 35.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 13.7 / 100 |
| Social Vulnerability | 66.6 / 100 |
| Community Resilience | 0.5 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Very Low |
| Wildfire | Relatively Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Relatively Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Low |
| Lightning | Very Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
15 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.3.
| Nov 3, 2002 | 16 km SSW of Butte, Nebraska | M4.3 | 149 km | 5 km |
| May 30, 2024 | 38 km NNW of Pierre, South Dakota | M3.7 | 115 km | 15 km |
| Jun 4, 2021 | 10 km NE of Anoka, Nebraska | M3.7 | 128 km | 5 km |
| Oct 25, 1990 | 8 km N of Plankinton, South Dakota | M3.6 | 80 km | 5 km |
| Aug 9, 2011 | 2 km S of Fort Pierre, South Dakota | M3.3 | 83 km | 5 km |
| Aug 5, 2022 | 4 km ENE of Draper, South Dakota | M3.2 | 88 km | 9 km |
| Jul 12, 1998 | 7 km E of Corn Creek, South Dakota | M3.1 | 148 km | 5 km |
| Jun 4, 2021 | 9 km ENE of Anoka, Nebraska | M3.1 | 130 km | 5 km |
| Jul 26, 2002 | 0 km WSW of Huron, South Dakota | M3.1 | 101 km | 5 km |
| Aug 15, 2017 | 8 km E of Agar, South Dakota | M3.0 | 98 km | 5 km |
| Feb 7, 2014 | 11 km NE of Bijou Hills, South Dakota | M3.0 | 57 km | 5 km |
| Jul 3, 1995 | 9 km SSW of Fort Thompson, South Dakota | M2.8 | 10 km | 5 km |
| Mar 20, 2010 | 9 km NNW of Springview, Nebraska | M2.7 | 133 km | 5 km |
| Apr 27, 2025 | 9 km NE of Burke, South Dakota | M2.5 | 91 km | 5 km |
| Jan 16, 2022 | 9 km NE of Plankinton, South Dakota | M2.5 | 87 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
302 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 1 fatality, 50 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 18, 2014 | EF4 | 80 km | 11.5 mi | 0 |
| May 5, 2007 | EF3 | 89 km | 4.0 mi | 0 |
| Aug 24, 2006 | EF3 | 65 km | 24.5 mi | 0 |
| Jun 24, 2003 | EF3 | 86 km | 6.0 mi | 0 |
| Jun 7, 1993 | EF3 | 91 km | 5.0 mi | 0 |
| Jun 16, 1992 | EF3 | 2 km | 2.0 mi | 0 |
| Jul 23, 1973 | EF3 | 82 km | 2.5 mi | 0 |
| Jul 24, 1971 | EF3 | 32 km | 2.5 mi | 0 |
| Jul 9, 1971 | EF3 | 26 km | 0.1 mi | 0 |
| Jul 9, 1971 | EF3 | 16 km | 0.1 mi | 0 |
| Jul 3, 1971 | EF3 | 28 km | 0.1 mi | 0 |
| May 8, 1965 | EF3 | 99 km | 1.5 mi | 0 |
| May 15, 1962 | EF3 | 95 km | 0.1 mi | 0 |
| Aug 30, 2020 | EF2 | 80 km | 1.6 mi | 1 |
| Jun 18, 2014 | EF2 | 41 km | 1.1 mi | 0 |
| Jun 18, 2014 | EF2 | 48 km | 0.8 mi | 0 |
| Jun 18, 2014 | EF2 | 67 km | 2.2 mi | 0 |
| May 22, 2010 | EF2 | 84 km | 2.9 mi | 0 |
| Aug 24, 2006 | EF2 | 58 km | 5.0 mi | 0 |
| Jun 29, 1993 | EF2 | 85 km | 5.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
14 wildfires (100+ acres) recorded within 100 km. Largest: OKREEK (11,115 acres, 2011).
| Year | Name | Acres Burned | Distance |
| 2011 | OKREEK | 11,115 | 89 km |
| 2006 | THOMPSON COMPLEX | 3,230 | 55 km |
| 2000 | CLOVER | 3,062 | 43 km |
| 2022 | HOLIDAY | 2,936 | 12 km |
| 2000 | GANN VALLEY | 2,534 | 42 km |
| 2000 | NOVOTNY AND WAGNER | 1,968 | 99 km |
| 2006 | FT PIERRE COMPLEX | 1,812 | 68 km |
| 2011 | HIGHWAY 47 | 1,800 | 9 km |
| 2005 | CHAOS | 1,539 | 6 km |
| 2014 | OKREEK | 1,273 | 81 km |
| 2000 | BAD HORSE | 1,215 | 31 km |
| 2005 | N HYDE | 1,204 | 74 km |
| 2023 | SDLDR-HFR-FY23-RX-BROKEN ARROW UNITS B-C-D-E-G-H-I | 1,185 | 85 km |
| 2009 | TAHOHPI WUI RX | 1,166 | 88 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 18°F (-8°C) | 0.3 in | Coldest, Driest |
| February | 22°F (-5°C) | 0.4 in | |
| March | 32°F (0°C) | 1.2 in | |
| April | 46°F (8°C) | 2.1 in | |
| May | 58°F (14°C) | 2.8 in | |
| June | 68°F (20°C) | 3.0 in | Wettest |
| July | 74°F (24°C) | 2.7 in | Warmest |
| August | 73°F (23°C) | 2.1 in | |
| September | 63°F (17°C) | 1.6 in | |
| October | 50°F (10°C) | 1.4 in | |
| November | 33°F (1°C) | 0.6 in | |
| December | 21°F (-6°C) | 0.4 in |
Fort Thompson has a seasonal temperature swing of 56°F / from 18°F in January to 74°F in July. Total annual precipitation is 18.5 inches, with June being the wettest month (3.0") and January the driest (0.3").