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Weather & Climate in Dennis, MA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Dennis experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 32°F in January while summers reach 73°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 44.7 inches. Air quality is rated Good with a median AQI of 37. The city sits at an elevation of 5 feet.
Temperature
32°F Jan (0°C)
73°F Jul (23°C)
| Annual Average | 51.5°F |
| 5% below US avg | |
| January Average | 32°F (0°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 5 ft (2 m) |
| Area | 5.1 sq mi (13.2 km²) |
| Population Density | 388/sq mi |
| Coordinates | 41.7302°N, 70.1974°W |
| Timezone | America/New_York |
| County | Barnstable County County |
| Nearest Airport | New Bedford Regional (EWB) 39 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 37.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 89.1 / 100 |
| Social Vulnerability | 34.5 / 100 |
| Community Resilience | 99.3 / 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 Low |
| Lightning | Relatively High |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
| Coastal Flood | Very High |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
16 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.3.
| Jan 12, 2015 | 0 km NE of Wauregan, Connecticut | M3.3 | 141 km | 5 km |
| Mar 22, 1996 | 2 km NE of Bristol, Rhode Island | M3.1 | 87 km | 12 km |
| Jan 10, 1999 | 2 km ENE of Merrimac, Massachusetts | M3.1 | 139 km | 2 km |
| Mar 12, 2002 | 52 km E of Chatham, Massachusetts | M3.0 | 73 km | 1 km |
| Jan 10, 1999 | 1 km NNE of Merrimac, Massachusetts | M3.0 | 140 km | 2 km |
| Jul 22, 2003 | 72 km NNE of Provincetown, Massachusetts | M3.0 | 105 km | 10 km |
| Jan 8, 1998 | 52 km ENE of Rockport, Massachusetts | M2.9 | 126 km | 25 km |
| Jun 7, 2010 | 29 km SE of York Beach, Maine | M2.9 | 144 km | 10 km |
| Mar 9, 2008 | 25 km SE of York Beach, Maine | M2.8 | 144 km | 0 km |
| Oct 11, 1990 | 5 km NNE of The Pinehills, Massachusetts | M2.7 | 38 km | 13 km |
| Oct 13, 1999 | 2 km E of Littleton Common, Massachusetts | M2.7 | 137 km | 2 km |
| Feb 15, 2018 | 0 km SE of East Kingston, New Hampshire | M2.7 | 148 km | 7 km |
| Apr 22, 1996 | 3 km NE of North Westport, Massachusetts | M2.6 | 72 km | 5 km |
| Jan 13, 2015 | 2 km E of Wauregan, Connecticut | M2.6 | 140 km | 9 km |
| Jun 7, 2002 | 3 km NNW of Hopedale, Massachusetts | M2.5 | 122 km | 5 km |
| Jan 23, 1990 | 3 km NNW of Boxborough, Massachusetts | M2.5 | 142 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
7 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 | 268 km |
| 2019 | Dorian | Category 2 | 98 mph | 289 km |
| 2014 | Arthur | Category 1 | 75 mph | 175 km |
| 2008 | Kyle | Category 1 | 86 mph | 271 km |
| 1996 | Edouard | Category 1 | 81 mph | 202 km |
| 1991 | Bob | Category 2 | 104 mph | 100 km |
| 1985 | Gloria | Category 1 | 86 mph | 217 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
38 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 1 fatality, 8 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Aug 28, 1970 | EF2 | 60 km | 1.0 mi | 0 |
| Nov 18, 1967 | EF2 | 64 km | 0.1 mi | 0 |
| Nov 21, 1956 | EF2 | 94 km | 0.1 mi | 0 |
| Dec 18, 1951 | EF2 | 49 km | 0.1 mi | 0 |
| Jun 26, 2024 | EF1 | 91 km | 0.6 mi | 0 |
| Aug 18, 2023 | EF1 | 80 km | 0.4 mi | 0 |
| Aug 8, 2023 | EF1 | 54 km | 0.9 mi | 0 |
| Jul 29, 2023 | EF1 | 90 km | 0.2 mi | 0 |
| Jul 23, 2019 | EF1 | 13 km | 5.5 mi | 0 |
| Jul 23, 2019 | EF1 | 10 km | 0.3 mi | 0 |
| Jul 23, 2019 | EF1 | 11 km | 2.8 mi | 0 |
| Oct 23, 2018 | EF1 | 87 km | 0.8 mi | 0 |
| Jul 23, 2008 | EF1 | 91 km | 4.3 mi | 0 |
| Jul 10, 1989 | EF1 | 78 km | 0.1 mi | 0 |
| Sep 16, 1986 | EF1 | 68 km | 0.1 mi | 0 |
| Aug 22, 1977 | EF1 | 10 km | 0.1 mi | 0 |
| Sep 6, 1973 | EF1 | 93 km | 1.1 mi | 0 |
| Aug 2, 1970 | EF1 | 90 km | 2.0 mi | 0 |
| Aug 9, 1968 | EF1 | 58 km | 1.0 mi | 0 |
| Aug 9, 1968 | EF1 | 96 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
1 wildfire (100+ acres) recorded within 100 km. Largest: NOMANS AERIAL RX (546 acres, 2008).
| Year | Name | Acres Burned | Distance |
| 2008 | NOMANS AERIAL RX | 546 | 74 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 32°F (0°C) | 3.7 in | |
| February | 31°F (-0°C) | 3.6 in | Coldest |
| March | 38°F (3°C) | 3.7 in | |
| April | 46°F (8°C) | 3.8 in | |
| May | 55°F (13°C) | 3.5 in | |
| June | 64°F (18°C) | 3.2 in | |
| July | 73°F (23°C) | 3.0 in | Warmest, Driest |
| August | 70°F (21°C) | 3.4 in | |
| September | 63°F (17°C) | 3.5 in | |
| October | 53°F (12°C) | 3.7 in | |
| November | 45°F (7°C) | 4.4 in | Wettest |
| December | 36°F (2°C) | 4.3 in |
Dennis has a seasonal temperature swing of 42°F / from 31°F in February to 73°F in July. Total annual precipitation is 43.7 inches, with November being the wettest month (4.4") and July the driest (3.0").