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Weather & Climate in St. Mary, MO
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St. Mary enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 30°F in January while summers reach 78°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 41.8 inches. The area receives 4.7 inches of snow annually. Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 453 feet.
Temperature
30°F Jan (-1°C)
78°F Jul (26°C)
| Annual Average | 55.8°F |
| 3% above US avg | |
| January Average | 30°F (-1°C) |
| July Average | 78°F (26°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 453 ft (138 m) |
| Area | 0.6 sq mi (1.6 km²) |
| Population Density | 425/sq mi |
| Coordinates | 37.8726°N, 89.9465°W |
| Timezone | America/Chicago |
| Nearest Airport | Farmington Regional (FAM) 25 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Earthquake History
166 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.8.
| Sep 26, 1990 | 4 km SE of Chaffee, Missouri | M4.8 | 85 km | 1 km |
| May 4, 1991 | 2 km NNW of Risco, Missouri | M4.5 | 145 km | 11 km |
| Feb 5, 1994 | 2 km WNW of Dongola, Illinois | M4.2 | 87 km | 16 km |
| Jun 6, 2003 | 1 km NE of Bardwell, Kentucky | M4.0 | 139 km | 3 km |
| Jun 7, 2011 | 18 km NNW of Potosi, Missouri | M3.9 | 87 km | 21 km |
| Feb 21, 2012 | 4 km SSE of Bertrand, Missouri | M3.9 | 120 km | 8 km |
| Mar 2, 2010 | 2 km ENE of East Prairie, Missouri | M3.7 | 131 km | 8 km |
| Jan 2, 2006 | 3 km NNE of Eldorado, Illinois | M3.6 | 134 km | 7 km |
| Jun 20, 2005 | 4 km WSW of Blandville, Kentucky | M3.6 | 135 km | 19 km |
| Sep 22, 2011 | 6 km E of Grandin, Missouri | M3.6 | 137 km | 11 km |
| Mar 15, 2017 | 9 km ESE of Wyatt, Missouri | M3.6 | 132 km | 8 km |
| Jul 16, 2004 | 6 km SE of Wyatt, Missouri | M3.5 | 131 km | 4 km |
| May 1, 2016 | 5 km SE of New Grand Chain, Illinois | M3.5 | 112 km | 16 km |
| Jun 15, 2004 | 3 km S of Canalou, Missouri | M3.5 | 130 km | 5 km |
| Sep 26, 1994 | 4 km ENE of Blandville, Kentucky | M3.4 | 136 km | 13 km |
| Mar 2, 1990 | 9 km NW of Vernon, Illinois | M3.4 | 128 km | 0 km |
| Aug 27, 1993 | 5 km SSE of Olympian Village, Missouri | M3.3 | 49 km | 22 km |
| Feb 6, 1993 | 6 km NNW of Catron, Missouri | M3.3 | 136 km | 8 km |
| Sep 27, 2019 | 4 km WSW of Howardville, Missouri | M3.3 | 149 km | 8 km |
| May 16, 2017 | 9 km ESE of Wyatt, Missouri | M3.3 | 133 km | 9 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
594 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 94 fatalities, 1,291 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Dec 18, 1957 | EF5 | 65 km | 5.4 mi | 1 |
| Feb 28, 2017 | EF4 | 17 km | 53.5 mi | 1 |
| Nov 17, 2013 | EF4 | 75 km | 10.6 mi | 2 |
| Sep 22, 2006 | EF4 | 24 km | 27.5 mi | 0 |
| May 29, 1982 | EF4 | 72 km | 17.0 mi | 10 |
| Apr 3, 1981 | EF4 | 96 km | 11.9 mi | 0 |
| Jun 22, 1969 | EF4 | 55 km | 15.1 mi | 4 |
| Feb 10, 1959 | EF4 | 93 km | 23.9 mi | 21 |
| Dec 18, 1957 | EF4 | 88 km | 16.8 mi | 1 |
| Dec 18, 1957 | EF4 | 45 km | 28.3 mi | 11 |
| May 26, 2024 | EF3 | 88 km | 4.9 mi | 0 |
| Dec 10, 2021 | EF3 | 99 km | 4.2 mi | 6 |
| Oct 24, 2021 | EF3 | 45 km | 16.7 mi | 0 |
| Oct 24, 2021 | EF3 | 54 km | 18.8 mi | 0 |
| Nov 17, 2013 | EF3 | 97 km | 14.3 mi | 0 |
| Dec 31, 2010 | EF3 | 83 km | 6.7 mi | 1 |
| Mar 11, 2006 | EF3 | 43 km | 5.1 mi | 0 |
| Mar 11, 2006 | EF3 | 8 km | 53.5 mi | 2 |
| May 6, 2003 | EF3 | 60 km | 2.0 mi | 0 |
| Apr 28, 2002 | EF3 | 78 km | 19.3 mi | 1 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: SMITH MILL HOLLOW (3,978 acres, 2022).
| Year | Name | Acres Burned | Distance |
| 2022 | SMITH MILL HOLLOW | 3,978 | 93 km |
| 2021 | COUNCIL BLUFF | 3,035 | 89 km |
| 2024 | COUNCIL BLUFF WEST RX | 2,846 | 89 km |
| 2005 | UNNAMED | 2,751 | 90 km |
| 2019 | UNNAMED | 2,688 | 98 km |
| 2010 | COUNCIL BLUFF LAKE | 2,651 | 89 km |
| 2006 | UNNAMED | 2,512 | 89 km |
| 2021 | RED SHALE UNIT RX | 2,123 | 79 km |
| 2021 | BEAR PAW | 2,080 | 95 km |
| 2024 | BEAR PAW RX | 2,067 | 95 km |
| 2004 | CICERO CREEK | 1,846 | 95 km |
| 2021 | BERRYMAN BLOCK B AND C | 1,728 | 98 km |
| 2015 | CARTY | 1,674 | 98 km |
| 2014 | UNNAMED | 1,627 | 75 km |
| 2019 | ATWOOD RIDGE RX | 1,622 | 75 km |
| 2015 | UNNAMED | 1,586 | 89 km |
| 2010 | DELBRIDGE SOUTH | 1,574 | 90 km |
| 2000 | UNNAMED | 1,552 | 65 km |
| 1999 | UNNAMED | 1,483 | 65 km |
| 2020 | UNNAMED | 1,334 | 90 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 30°F (-1°C) | 2.2 in | Coldest, Driest |
| February | 35°F (2°C) | 2.5 in | |
| March | 45°F (7°C) | 4.1 in | |
| April | 56°F (13°C) | 3.8 in | |
| May | 65°F (19°C) | 4.3 in | Wettest |
| June | 74°F (23°C) | 3.7 in | |
| July | 78°F (26°C) | 4.0 in | Warmest |
| August | 76°F (25°C) | 3.5 in | |
| September | 70°F (21°C) | 3.5 in | |
| October | 58°F (15°C) | 2.9 in | |
| November | 46°F (8°C) | 4.0 in | |
| December | 36°F (2°C) | 3.5 in |
St. Mary has a seasonal temperature swing of 48°F / from 30°F in January to 78°F in July. Total annual precipitation is 41.8 inches, with May being the wettest month (4.3") and January the driest (2.2").