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Weather & Climate in Colchester, CT
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Colchester experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 27°F in January while summers reach 72°F in July. The area gets 275 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 43.3 inches. Air quality is rated Good with a median AQI of 39. The city sits at an elevation of 460 feet.
Temperature
27°F Jan (-3°C)
72°F Jul (22°C)
| Annual Average | 49.9°F |
| 8% below US avg | |
| January Average | 27°F (-3°C) |
| July Average | 72°F (22°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 460 ft (140 m) |
| Area | 4.5 sq mi (11.6 km²) |
| Population Density | 1,034/sq mi |
| Coordinates | 41.5776°N, 72.3327°W |
| Timezone | America/New_York |
| County | Southeastern Connecticut Planning Region County |
| Nearest Airport | Bradley International (BDL) 31 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 39.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 88.7 / 100 |
| Social Vulnerability | 26.8 / 100 |
| Community Resilience | 86.4 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively High |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
| Coastal Flood | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
16 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.7.
| Oct 2, 1994 | 6 km W of Hardwick, Massachusetts | M3.7 | 86 km | 10 km |
| Jan 12, 2015 | 0 km NE of Wauregan, Connecticut | M3.3 | 41 km | 5 km |
| Jun 16, 2000 | 5 km NE of Granville, Massachusetts | M3.3 | 71 km | 10 km |
| Oct 2, 1994 | 1 km NW of Hardwick, Massachusetts | M3.3 | 88 km | 10 km |
| Mar 22, 1996 | 2 km NE of Bristol, Rhode Island | M3.1 | 92 km | 12 km |
| Apr 9, 2019 | 63 km SSE of Sagaponack, New York | M3.0 | 134 km | 7 km |
| Oct 28, 1991 | 3 km WNW of Stamford, Connecticut | M3.0 | 118 km | 10 km |
| Mar 10, 1992 | 2 km SW of Napeague, New York | M2.8 | 68 km | 10 km |
| Apr 12, 1991 | 2 km ENE of North Castle, New York | M2.7 | 120 km | 9 km |
| Oct 13, 1999 | 2 km E of Littleton Common, Massachusetts | M2.7 | 131 km | 2 km |
| Aug 14, 2014 | 6 km SW of Deep River Center, Connecticut | M2.7 | 29 km | 4 km |
| Aug 22, 2000 | 2 km WSW of Brewster Hill, New York | M2.6 | 109 km | 7 km |
| Apr 22, 1996 | 3 km NE of North Westport, Massachusetts | M2.6 | 106 km | 5 km |
| Jan 13, 2015 | 2 km E of Wauregan, Connecticut | M2.6 | 42 km | 9 km |
| Jun 7, 2002 | 3 km NNW of Hopedale, Massachusetts | M2.5 | 91 km | 5 km |
| Jan 23, 1990 | 3 km NNW of Boxborough, Massachusetts | M2.5 | 124 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Hurricane History
4 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 2.
| Year | Name | Category | Max Wind | Closest |
| 2021 | Henri | Category 1 | 75 mph | 267 km |
| 2014 | Arthur | Category 1 | 75 mph | 269 km |
| 1991 | Bob | Category 2 | 109 mph | 74 km |
| 1985 | Gloria | Category 1 | 86 mph | 53 km |
Source: NOAA IBTrACS (Category 1+, 1980-2026).
Tornado History
220 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 10 fatalities, 955 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jul 10, 1989 | EF4 | 52 km | 3.0 mi | 0 |
| Oct 3, 1979 | EF4 | 44 km | 11.3 mi | 3 |
| Jun 1, 2011 | EF3 | 68 km | 37.6 mi | 3 |
| Sep 13, 1971 | EF3 | 88 km | 0.5 mi | 0 |
| Jul 29, 1971 | EF3 | 60 km | 0.1 mi | 0 |
| Oct 3, 1970 | EF3 | 85 km | 35.4 mi | 1 |
| May 24, 1962 | EF3 | 66 km | 11.6 mi | 1 |
| May 10, 1954 | EF3 | 40 km | 0.3 mi | 0 |
| Jun 9, 1953 | EF3 | 81 km | 28.0 mi | 0 |
| Aug 21, 1951 | EF3 | 14 km | 0.1 mi | 0 |
| Aug 18, 2023 | EF2 | 68 km | 9.1 mi | 0 |
| Jun 23, 2001 | EF2 | 70 km | 0.5 mi | 0 |
| Aug 8, 1999 | EF2 | 66 km | 4.0 mi | 0 |
| Jul 3, 1997 | EF2 | 96 km | 3.7 mi | 0 |
| Jul 3, 1997 | EF2 | 99 km | 4.5 mi | 0 |
| Jul 10, 1989 | EF2 | 92 km | 0.2 mi | 0 |
| Jul 10, 1989 | EF2 | 87 km | 10.0 mi | 0 |
| Jul 10, 1989 | EF2 | 66 km | 5.0 mi | 0 |
| Aug 7, 1986 | EF2 | 76 km | 4.0 mi | 0 |
| Jul 5, 1984 | EF2 | 52 km | 3.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Tsunami History
1 tsunami recorded within 500 km. Highest wave on record: 0.3 m (1 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1964 | LONG ISLAND, NY | Meteorological | 0.3 m | - | 108 km |
Source: NOAA/NCEI Historical Tsunami Database.
Wildfire History
1 wildfire (100+ acres) recorded within 100 km. Largest: CRESCENT BOW FIRE (1,068 acres, 2012).
| Year | Name | Acres Burned | Distance |
| 2012 | CRESCENT BOW FIRE | 1,068 | 87 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 27°F (-3°C) | 4.3 in | Coldest |
| February | 27°F (-3°C) | 3.6 in | Driest |
| March | 36°F (2°C) | 4.4 in | |
| April | 46°F (8°C) | 4.4 in | |
| May | 56°F (13°C) | 4.1 in | |
| June | 65°F (18°C) | 3.9 in | |
| July | 72°F (22°C) | 3.9 in | Warmest |
| August | 70°F (21°C) | 4.1 in | |
| September | 62°F (17°C) | 4.1 in | |
| October | 52°F (11°C) | 4.3 in | |
| November | 43°F (6°C) | 4.7 in | Wettest |
| December | 32°F (0°C) | 4.4 in |
Colchester has a seasonal temperature swing of 45°F / from 27°F in January to 72°F in July. Total annual precipitation is 50.0 inches, with November being the wettest month (4.7") and February the driest (3.6").