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Weather & Climate in Chelmsford, ON
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Chelmsford has a cool climate with an average annual temperature of 38°F (4°C). Winters average 8°F in January while summers reach 65°F in July. The area gets 273 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 34.8 inches. The area receives 12.8 inches of snow annually. The city sits at an elevation of 883 feet.
Temperature
8°F Jan (-14°C)
65°F Jul (18°C)
| Annual Average | 38.4°F |
| 29% below US avg | |
| January Average | 8°F (-14°C) |
| July Average | 65°F (18°C) |
| Sunny Days | 273 days/yr |
Geography
| Elevation | 883 ft (269 m) |
| Area | 1,743.7 sq mi (4,516.3 km²) |
| Population Density | 0/sq mi |
| Coordinates | 46.5834°N, 81.1998°W |
| Timezone | America/Toronto |
Precipitation & Snow
Air Quality
Earthquake History
6 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.9.
| Mar 9, 1998 | Ontario, Canada | M3.9 | 14 km | 1 km |
| Aug 5, 2014 | 6 km NNW of Lively, Canada | M3.8 | 11 km | 5 km |
| Mar 13, 2005 | 5 km N of Greater Sudbury, Canada | M3.6 | 18 km | 18 km |
| May 25, 1998 | 3 km NW of Lively, Canada | M3.4 | 14 km | 1 km |
| Aug 5, 2014 | 5 km NNW of Lively, Canada | M3.3 | 12 km | 12 km |
| Feb 8, 2019 | 7 km SW of Azilda, Canada | M3.1 | 9 km | 2 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 8°F (-14°C) | 2.4 in | Coldest |
| February | 11°F (-12°C) | 1.8 in | Driest |
| March | 22°F (-6°C) | 2.6 in | |
| April | 37°F (3°C) | 2.4 in | |
| May | 51°F (10°C) | 3.2 in | |
| June | 60°F (16°C) | 3.0 in | |
| July | 65°F (18°C) | 2.9 in | Warmest |
| August | 63°F (17°C) | 3.2 in | |
| September | 55°F (13°C) | 3.9 in | Wettest |
| October | 44°F (6°C) | 3.5 in | |
| November | 31°F (-1°C) | 3.2 in | |
| December | 15°F (-9°C) | 2.9 in |
Chelmsford has a seasonal temperature swing of 57°F / from 8°F in January to 65°F in July. Total annual precipitation is 34.8 inches, with September being the wettest month (3.9") and February the driest (1.8").