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Weather & Climate in Sinai, SD
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Sinai has a cool climate with an average annual temperature of 45°F (7°C). Winters average 15°F in January while summers reach 72°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 26.2 inches (drier than the 38-inch national average). Air quality is rated Good with a median AQI of 35. The city sits at an elevation of 1,777 feet.
Temperature
15°F Jan (-10°C)
72°F Jul (22°C)
| Annual Average | 44.7°F |
| 17% below US avg | |
| January Average | 15°F (-10°C) |
| July Average | 72°F (22°C) |
| Sunny Days | 276 days/yr |
Geography
| Elevation | 1,777 ft (542 m) |
| Area | 0.4 sq mi (1.0 km²) |
| Population Density | 595/sq mi |
| Coordinates | 44.2445°N, 97.0440°W |
| Timezone | America/Chicago |
| County | Lake County County |
| Nearest Airport | Brookings Regional (BKX) 12 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 35.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 32.6 / 100 |
| Social Vulnerability | 25.9 / 100 |
| Community Resilience | 74.2 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Moderate |
| 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
4 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.6.
| Oct 25, 1990 | 8 km N of Plankinton, South Dakota | M3.6 | 125 km | 5 km |
| Jul 26, 2002 | 0 km WSW of Huron, South Dakota | M3.1 | 94 km | 5 km |
| Jan 4, 2021 | 5 km N of Tyndall, South Dakota | M3.1 | 149 km | 5 km |
| Jan 16, 2022 | 9 km NE of Plankinton, South Dakota | M2.5 | 121 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
530 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 8 fatalities, 298 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 16, 1992 | EF5 | 96 km | 16.0 mi | 1 |
| Jun 24, 2003 | EF4 | 58 km | 10.0 mi | 0 |
| May 30, 1998 | EF4 | 75 km | 14.0 mi | 6 |
| Jun 7, 1993 | EF4 | 45 km | 10.0 mi | 0 |
| Jun 7, 1993 | EF4 | 59 km | 54.0 mi | 0 |
| Jun 16, 1992 | EF4 | 97 km | 7.0 mi | 0 |
| Jul 7, 1955 | EF4 | 72 km | 30.0 mi | 1 |
| May 30, 2022 | EF3 | 64 km | 13.3 mi | 0 |
| Jun 24, 2003 | EF3 | 80 km | 3.5 mi | 0 |
| Jun 7, 1993 | EF3 | 53 km | 5.0 mi | 0 |
| Jun 7, 1993 | EF3 | 28 km | 6.0 mi | 0 |
| Jun 7, 1993 | EF3 | 41 km | 6.0 mi | 0 |
| May 7, 1993 | EF3 | 75 km | 10.0 mi | 0 |
| Jun 16, 1992 | EF3 | 99 km | 12.0 mi | 0 |
| Jun 16, 1992 | EF3 | 15 km | 4.0 mi | 0 |
| Jun 16, 1992 | EF3 | 43 km | 3.0 mi | 0 |
| Apr 20, 1985 | EF3 | 85 km | 8.0 mi | 0 |
| May 12, 1984 | EF3 | 89 km | 27.0 mi | 0 |
| Jul 18, 1983 | EF3 | 74 km | 0.5 mi | 0 |
| Jun 15, 1970 | EF3 | 13 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 15°F (-10°C) | 0.5 in | Coldest, Driest |
| February | 19°F (-7°C) | 0.6 in | |
| March | 31°F (-1°C) | 1.6 in | |
| April | 45°F (7°C) | 2.2 in | |
| May | 58°F (14°C) | 2.9 in | |
| June | 67°F (19°C) | 4.0 in | Wettest |
| July | 72°F (22°C) | 3.2 in | Warmest |
| August | 69°F (21°C) | 2.9 in | |
| September | 60°F (15°C) | 2.4 in | |
| October | 47°F (8°C) | 1.8 in | |
| November | 30°F (-1°C) | 1.0 in | |
| December | 17°F (-8°C) | 0.6 in |
Sinai has a seasonal temperature swing of 57°F / from 15°F in January to 72°F in July. Total annual precipitation is 23.6 inches, with June being the wettest month (4.0") and January the driest (0.5").