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Weather & Climate in St. Thomas, ON
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St. Thomas experiences four distinct seasons with an average annual temperature of 49°F (9°C). Winters average 26°F in January while summers reach 71°F in July. The area gets 265 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 37.8 inches. The area receives 35.1 inches of snow annually, a moderate snowfall amount. The city sits at an elevation of 764 feet.
Temperature
26°F Jan (-4°C)
71°F Jul (22°C)
| Annual Average | 48.9°F |
| 9% below US avg | |
| January Average | 26°F (-4°C) |
| July Average | 71°F (22°C) |
| Sunny Days | 265 days/yr |
Geography
| Elevation | 764 ft (233 m) |
| Area | 13.8 sq mi (35.6 km²) |
| Population Density | 3,116/sq mi |
| Coordinates | 42.7736°N, 81.1804°W |
| Timezone | America/Toronto |
Precipitation & Snow
Air Quality
Earthquake History
34 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.0.
| Jun 10, 2019 | 1 km NW of Timberlake, Ohio | M4.0 | 124 km | 2 km |
| Jan 26, 2001 | 8 km NNW of Edgewood, Ohio | M3.9 | 98 km | 5 km |
| Jun 30, 2003 | 6 km NW of Perry, Ohio | M3.6 | 108 km | 5 km |
| Oct 16, 1993 | 8 km SSE of Madison, Ohio | M3.6 | 120 km | 5 km |
| Aug 28, 2023 | 7 km SE of Madison, Ohio | M3.6 | 117 km | 5 km |
| Jun 20, 2006 | 9 km WNW of North Perry, Ohio | M3.5 | 104 km | 5 km |
| Mar 15, 1992 | 15 km NW of North Perry, Ohio | M3.5 | 96 km | 5 km |
| Jun 3, 2001 | 3 km N of Edgewood, Ohio | M3.4 | 102 km | 5 km |
| Jan 26, 1991 | 1 km NNE of Mayfield Heights, Ohio | M3.4 | 139 km | 5 km |
| Jun 30, 2004 | 2 km WNW of Madison, Ohio | M3.3 | 111 km | 5 km |
| Jul 1, 2013 | 5 km NNW of Fairport Harbor, Ohio | M3.2 | 109 km | 5 km |
| Jan 9, 2008 | 6 km WNW of Mentor-on-the-Lake, Ohio | M3.1 | 119 km | 5 km |
| Mar 11, 2006 | 8 km NNW of Mentor-on-the-Lake, Ohio | M3.1 | 112 km | 5 km |
| Apr 25, 2010 | 2 km WNW of Madison, Ohio | M3.0 | 111 km | 5 km |
| Feb 23, 2011 | 18 km NE of Leamington, Canada | M3.0 | 123 km | 5 km |
| Feb 23, 1995 | 3 km W of Ashtabula, Ohio | M2.9 | 105 km | 5 km |
| Jan 4, 2022 | 3 km NW of Timberlake, Ohio | M2.8 | 123 km | 5 km |
| Sep 22, 1999 | 16 km NW of Mentor-on-the-Lake, Ohio | M2.8 | 108 km | 18 km |
| Mar 8, 2013 | 5 km NNW of Timberlake, Ohio | M2.7 | 121 km | 5 km |
| Apr 28, 2002 | Ohio | M2.7 | 104 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tsunami History
2 tsunamis recorded within 500 km. Highest wave on record: 2.7 m (9 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1823 | LAKE ERIE | Unknown | 2.7 m | - | 56 km |
| 1952 | LAKE HURON, MI | Avalanche | 1.5 m | - | 106 km |
Source: NOAA/NCEI Historical Tsunami Database.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 26°F (-4°C) | 2.7 in | |
| February | 23°F (-5°C) | 2.3 in | Coldest, Driest |
| March | 32°F (0°C) | 2.8 in | |
| April | 44°F (7°C) | 3.4 in | |
| May | 56°F (13°C) | 3.3 in | |
| June | 65°F (18°C) | 3.6 in | |
| July | 71°F (22°C) | 3.3 in | Warmest |
| August | 68°F (20°C) | 3.5 in | |
| September | 61°F (16°C) | 3.7 in | |
| October | 50°F (10°C) | 3.2 in | |
| November | 40°F (4°C) | 3.9 in | Wettest |
| December | 29°F (-2°C) | 3.5 in |
St. Thomas has a seasonal temperature swing of 48°F / from 23°F in February to 71°F in July. Total annual precipitation is 39.0 inches, with November being the wettest month (3.9") and February the driest (2.3").