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Weather & Climate in Union, NH
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Union experiences four distinct seasons with an average annual temperature of 47°F (9°C). Winters average 24°F in January while summers reach 71°F in July. The area gets 246 sunny days per year, above the national average. Annual precipitation totals 46.3 inches (wetter than the 38-inch national average). The area receives 56.6 inches of snow annually, making winter weather a significant factor for residents. Air quality is rated Good with a median AQI of 37. The city sits at an elevation of 481 feet.
Temperature
24°F Jan (-5°C)
71°F Jul (22°C)
| Annual Average | 47.4°F |
| 12% below US avg | |
| January Average | 24°F (-5°C) |
| July Average | 71°F (22°C) |
| Sunny Days | 246 days/yr |
Geography
| Elevation | 481 ft (147 m) |
| Area | 0.3 sq mi (0.8 km²) |
| Population Density | 1,142/sq mi |
| Coordinates | 43.4912°N, 71.0231°W |
| Timezone | America/New_York |
| County | Strafford County County |
| Nearest Airport | Sanford Seacoast Regional (SFM) 17 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 37.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 64.1 / 100 |
| Social Vulnerability | 16.6 / 100 |
| Community Resilience | 73.5 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Very Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively High |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
| Coastal Flood | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
46 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.7.
| Oct 16, 2012 | 5 km W of Hollis Center, Maine | M4.7 | 32 km | 16 km |
| Aug 21, 1996 | 12 km N of Livermore, New Hampshire | M3.8 | 81 km | 10 km |
| Jan 27, 2025 | 9 km SE of York Harbor, Maine | M3.8 | 60 km | 11 km |
| Jun 16, 1995 | 8 km N of Lisbon, New Hampshire | M3.8 | 114 km | 5 km |
| Jan 17, 2000 | 4 km NNE of Dixfield, Maine | M3.6 | 129 km | 16 km |
| Jan 3, 2000 | 4 km W of Leeds, Maine | M3.5 | 114 km | 10 km |
| Oct 6, 1992 | 1 km SW of Canterbury, New Hampshire | M3.4 | 49 km | 5 km |
| Sep 26, 2010 | 2 km SW of Canterbury, New Hampshire | M3.2 | 49 km | 5 km |
| Jan 10, 1999 | 2 km ENE of Merrimac, Massachusetts | M3.1 | 73 km | 2 km |
| Sep 5, 1994 | 13 km NNE of Monhegan, Maine | M3.1 | 150 km | 5 km |
| Jan 10, 1999 | 1 km NNE of Merrimac, Massachusetts | M3.0 | 72 km | 2 km |
| Jan 27, 2000 | 3 km WNW of Fremont, New Hampshire | M3.0 | 56 km | 1 km |
| Nov 20, 1994 | 4 km WNW of Norway, Maine | M3.0 | 89 km | 5 km |
| Jul 22, 2003 | 72 km NNE of Provincetown, Massachusetts | M3.0 | 143 km | 10 km |
| Jan 8, 1998 | 52 km ENE of Rockport, Massachusetts | M2.9 | 107 km | 25 km |
| Apr 25, 2023 | 4 km SW of Center Sandwich, New Hampshire | M2.9 | 49 km | 8 km |
| Jun 7, 2010 | 29 km SE of York Beach, Maine | M2.9 | 78 km | 10 km |
| Feb 4, 2022 | 0 km SSW of Gorham, New Hampshire | M2.9 | 100 km | 8 km |
| Sep 28, 2002 | 2 km N of Wilton, New Hampshire | M2.8 | 90 km | 5 km |
| Mar 9, 2008 | 25 km SE of York Beach, Maine | M2.8 | 75 km | 0 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
2 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 2.
| Year | Name | Category | Max Wind | Closest |
| 1991 | Bob | Category 2 | 104 mph | 108 km |
| 1985 | Gloria | Category 1 | 86 mph | 229 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
114 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 1 fatality, 38 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Aug 25, 1969 | EF3 | 69 km | 5.7 mi | 0 |
| Jun 9, 1953 | EF3 | 58 km | 1.5 mi | 0 |
| Jul 24, 2008 | EF2 | 45 km | 50.5 mi | 1 |
| May 21, 2006 | EF2 | 65 km | 0.1 mi | 0 |
| Jul 6, 1999 | EF2 | 33 km | 7.5 mi | 0 |
| May 31, 1998 | EF2 | 91 km | 0.5 mi | 0 |
| Jul 3, 1997 | EF2 | 90 km | 2.0 mi | 0 |
| Jun 22, 1981 | EF2 | 14 km | 8.7 mi | 0 |
| May 3, 1976 | EF2 | 43 km | 1.0 mi | 0 |
| May 11, 1973 | EF2 | 75 km | 0.5 mi | 0 |
| Jul 21, 1972 | EF2 | 96 km | 7.6 mi | 0 |
| Jul 3, 1972 | EF2 | 34 km | 1.0 mi | 0 |
| Jul 17, 1968 | EF2 | 97 km | 0.1 mi | 0 |
| Oct 10, 1966 | EF2 | 21 km | 0.2 mi | 0 |
| Aug 28, 1965 | EF2 | 91 km | 2.0 mi | 0 |
| Jul 18, 1963 | EF2 | 19 km | 0.1 mi | 0 |
| Jun 9, 1963 | EF2 | 67 km | 10.0 mi | 0 |
| May 14, 1963 | EF2 | 21 km | 8.7 mi | 0 |
| Jul 2, 1961 | EF2 | 70 km | 2.0 mi | 0 |
| Jul 2, 1961 | EF2 | 76 km | 5.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Tsunami History
1 tsunami recorded within 500 km. Highest wave on record: 3.6 m (12 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 2008 | MAINE | Avalanche | 3.6 m | — | 112 km |
Source: NOAA/NCEI Historical Tsunami Database.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 24°F (-5°C) | 3.3 in | Driest |
| February | 23°F (-5°C) | 3.4 in | Coldest |
| March | 32°F (0°C) | 3.5 in | |
| April | 43°F (6°C) | 4.0 in | |
| May | 54°F (12°C) | 3.9 in | |
| June | 63°F (17°C) | 3.6 in | |
| July | 71°F (22°C) | 3.6 in | Warmest |
| August | 67°F (19°C) | 3.7 in | |
| September | 58°F (15°C) | 3.4 in | |
| October | 47°F (9°C) | 4.1 in | |
| November | 37°F (3°C) | 4.8 in | Wettest |
| December | 26°F (-3°C) | 4.0 in |
Union has a seasonal temperature swing of 48°F / from 23°F in February to 71°F in July. Total annual precipitation is 45.3 inches, with November being the wettest month (4.8") and January the driest (3.3").