Weather & Climate in Arnold, MO
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Arnold enjoys a temperate climate with an average annual temperature of 57°F (14°C). Winters average 32°F in January while summers reach 79°F in July. Annual precipitation totals 40.8 inches. The area receives 10.2 inches of snow annually. The city sits at an elevation of 600 feet.
Temperature
32°F Jan (0°C)
79°F Jul (26°C)
| Annual Average | 56.5°F |
| 5% above US avg | |
| January Average | 32°F (0°C) |
| July Average | 79°F (26°C) |
Geography
| Elevation | 600 ft (183 m) |
| Area | 11.9 sq mi (30.9 km²) |
| Population Density | 1,811/sq mi |
| Coordinates | 38.4328°N, 90.3776°W |
| Timezone | America/Chicago |
| Nearest Airport | St Louis Lambert International (STL) 22 miles away |
Precipitation & Snow
Air Quality
Earthquake History
44 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.9.
| Jun 7, 2011 | 18 km NNW of Potosi, Missouri | M3.9 | 61 km | 21 km |
| Mar 2, 1990 | 9 km NW of Vernon, Illinois | M3.4 | 115 km | 0 km |
| Aug 27, 1993 | 5 km SSE of Olympian Village, Missouri | M3.3 | 38 km | 22 km |
| Oct 24, 1990 | 5 km ENE of Woodlawn, Illinois | M3.2 | 123 km | 1 km |
| Jan 29, 1993 | 7 km WNW of Brownstown, Illinois | M3.2 | 135 km | 5 km |
| Dec 27, 1992 | 2 km E of Pocahontas, Missouri | M3.2 | 123 km | 10 km |
| Apr 6, 1994 | 2 km NE of Tamaroa, Illinois | M3.2 | 106 km | 15 km |
| Jul 1, 2017 | 9 km SSE of Mulberry Grove, Illinois | M3.1 | 110 km | 17 km |
| Mar 12, 2002 | 6 km S of Marble Hill, Missouri | M3.1 | 137 km | 10 km |
| Jan 23, 1991 | 3 km WSW of Logan, Illinois | M3.1 | 143 km | 1 km |
| Jun 27, 2005 | 6 km E of Grand Tower, Illinois | M3.0 | 122 km | 10 km |
| Feb 28, 1994 | 5 km NW of Harrison, Illinois | M3.0 | 110 km | 5 km |
| May 18, 2006 | 9 km SSE of De Soto, Missouri | M2.9 | 44 km | 6 km |
| Sep 5, 1995 | 3 km N of Woodlawn, Illinois | M2.9 | 117 km | 4 km |
| Sep 5, 2004 | 3 km WNW of Saint Peter, Illinois | M2.9 | 139 km | 33 km |
| Jul 8, 2003 | 1 km N of Leasburg, Missouri | M2.9 | 88 km | 4 km |
| Apr 29, 2022 | 1 km SSW of Peerless Park, Missouri | M2.8 | 15 km | 8 km |
| Mar 28, 2024 | 1 km NNE of Germantown, Illinois | M2.8 | 75 km | 24 km |
| Aug 26, 1992 | 5 km W of Frohna, Missouri | M2.8 | 107 km | 2 km |
| Sep 13, 1997 | 3 km SSE of Darmstadt, Illinois | M2.8 | 60 km | 16 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
581 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 76 fatalities, 1,214 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Feb 28, 2017 | EF4 | 85 km | 53.5 mi | 1 |
| Nov 17, 2013 | EF4 | 81 km | 10.6 mi | 2 |
| Apr 22, 2011 | EF4 | 35 km | 21.3 mi | 0 |
| Sep 22, 2006 | EF4 | 97 km | 27.5 mi | 0 |
| Apr 3, 1981 | EF4 | 39 km | 11.9 mi | 0 |
| Jun 22, 1969 | EF4 | 80 km | 15.1 mi | 4 |
| Jun 22, 1969 | EF4 | 83 km | 20.2 mi | 2 |
| Jan 24, 1967 | EF4 | 31 km | 25.0 mi | 3 |
| Feb 10, 1959 | EF4 | 22 km | 23.9 mi | 21 |
| Feb 24, 1956 | EF4 | 47 km | 77.6 mi | 6 |
| Dec 10, 2021 | EF3 | 50 km | 24.8 mi | 1 |
| Dec 10, 2021 | EF3 | 46 km | 4.2 mi | 6 |
| Oct 24, 2021 | EF3 | 81 km | 16.7 mi | 0 |
| Oct 24, 2021 | EF3 | 99 km | 18.8 mi | 0 |
| May 31, 2013 | EF3 | 43 km | 31.7 mi | 0 |
| May 31, 2013 | EF3 | 46 km | 10.6 mi | 0 |
| Dec 31, 2010 | EF3 | 10 km | 6.7 mi | 1 |
| Mar 13, 2006 | EF3 | 94 km | 6.0 mi | 0 |
| Mar 11, 2006 | EF3 | 35 km | 5.1 mi | 0 |
| Mar 11, 2006 | EF3 | 76 km | 53.5 mi | 2 |
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 | 76 km |
| 2021 | COUNCIL BLUFF | 3,035 | 94 km |
| 2024 | COUNCIL BLUFF WEST RX | 2,846 | 94 km |
| 2005 | UNNAMED | 2,751 | 89 km |
| 2019 | UNNAMED | 2,688 | 79 km |
| 2010 | COUNCIL BLUFF LAKE | 2,651 | 94 km |
| 2006 | UNNAMED | 2,512 | 94 km |
| 2021 | BEAR PAW | 2,080 | 89 km |
| 2024 | BEAR PAW RX | 2,067 | 89 km |
| 2004 | CICERO CREEK | 1,846 | 71 km |
| 2021 | BERRYMAN BLOCK B AND C | 1,728 | 81 km |
| 2015 | UNNAMED | 1,586 | 89 km |
| 2010 | DELBRIDGE SOUTH | 1,574 | 89 km |
| 2000 | UNNAMED | 1,552 | 90 km |
| 1999 | UNNAMED | 1,483 | 90 km |
| 2024 | HARMON SPRING RX | 1,330 | 78 km |
| 2018 | UNNAMED | 1,285 | 78 km |
| 2013 | UNNAMED | 1,196 | 89 km |
| 2022 | JOHNSON MOUNTAIN | 1,155 | 93 km |
| 2024 | RENAULT | 1,085 | 78 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 32°F (0°C) | 2.5 in | Coldest |
| February | 37°F (3°C) | 2.0 in | Driest |
| March | 46°F (8°C) | 3.3 in | |
| April | 57°F (14°C) | 4.5 in | |
| May | 67°F (19°C) | 4.8 in | Wettest |
| June | 75°F (24°C) | 4.4 in | |
| July | 79°F (26°C) | 3.7 in | Warmest |
| August | 77°F (25°C) | 3.7 in | |
| September | 69°F (21°C) | 3.4 in | |
| October | 58°F (14°C) | 3.1 in | |
| November | 46°F (8°C) | 3.3 in | |
| December | 36°F (2°C) | 2.3 in |
Arnold has a seasonal temperature swing of 47°F / from 32°F in January to 79°F in July. Total annual precipitation is 40.8 inches, with May being the wettest month (4.8") and February the driest (2.0").