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Weather & Climate in Portsmouth, United Kingdom
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Portsmouth experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 40°F in January while summers reach 61°F in July. The area gets 229 sunny days per year, above the national average. Annual precipitation totals 44.5 inches. The area receives 5.7 inches of snow annually. The city sits at an elevation of 20 feet.
Temperature
40°F Jan (5°C)
61°F Jul (16°C)
| Annual Average | 51.7°F |
| 4% below US avg | |
| January Average | 40°F (5°C) |
| July Average | 61°F (16°C) |
| Sunny Days | 229 days/yr |
Geography
| Elevation | 20 ft (6 m) |
| Area | 15.5 sq mi (40.2 km²) |
| Population Density | 13,391/sq mi |
| Coordinates | 50.7990°N, 1.0913°W |
| Timezone | Europe/London |
Precipitation & Snow
Air Quality
Earthquake History
28 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.6.
| Oct 6, 1999 | 34 km NNW of Fécamp, France | M4.6 | 127 km | 1 km |
| Jul 14, 2011 | 62 km SSE of Ventnor, United Kingdom | M3.9 | 79 km | 10 km |
| Jan 29, 2004 | 2 km E of North Petherton, United Kingdom | M3.7 | 136 km | 7 km |
| May 12, 1994 | 4 km S of Shipston on Stour, United Kingdom | M3.7 | 141 km | 10 km |
| Jan 29, 2004 | 2 km E of North Petherton, United Kingdom | M3.6 | 136 km | 7 km |
| Sep 23, 2003 | 41 km WNW of Étretat, France | M3.6 | 119 km | 10 km |
| Sep 24, 2003 | 22 km WNW of Cauville-sur-Mer, France | M3.5 | 140 km | 17 km |
| Jun 16, 1998 | 18 km NNW of Yport, France | M3.3 | 136 km | 5 km |
| Sep 9, 1995 | 0 km WNW of East Wittering, United Kingdom | M3.3 | 15 km | 10 km |
| Jan 29, 2004 | 2 km E of North Petherton, United Kingdom | M3.3 | 136 km | 7 km |
| Feb 27, 2019 | 3 km SE of Dorking, United Kingdom | M3.3 | 72 km | 10 km |
| May 19, 2019 | 7 km ESE of Swanage, United Kingdom | M3.0 | 60 km | 10 km |
| Nov 26, 1991 | 50 km N of Urville-Nacqueville, France | M3.0 | 86 km | 10 km |
| Aug 26, 2002 | 40 km NNW of Étretat, France | M3.0 | 113 km | 4 km |
| Mar 18, 2001 | 8 km W of Marlborough, United Kingdom | M2.9 | 88 km | 10 km |
| Jan 27, 2015 | 1 km ENE of Winchester, United Kingdom | M2.9 | 34 km | 3 km |
| Mar 23, 1998 | 11 km W of Chickerell, United Kingdom | M2.9 | 113 km | 5 km |
| Jul 16, 2005 | 3 km WSW of Southwater, United Kingdom | M2.9 | 54 km | 5 km |
| Dec 31, 1992 | 38 km WNW of Étretat, France | M2.8 | 123 km | 10 km |
| Apr 1, 2018 | 4 km E of Holmwood, United Kingdom | M2.7 | 72 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tsunami History
1 tsunami recorded within 500 km. Highest wave on record: 0.4 m (1 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 2011 | PLYMOUTH, ENGLAND | Avalanche | 0.4 m | — | 139 km |
Source: NOAA/NCEI Historical Tsunami Database.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 40°F (5°C) | 3.6 in | Coldest |
| February | 41°F (5°C) | 2.4 in | |
| March | 44°F (7°C) | 2.6 in | |
| April | 48°F (9°C) | 2.0 in | |
| May | 54°F (12°C) | 1.8 in | |
| June | 59°F (15°C) | 2.1 in | |
| July | 61°F (16°C) | 1.7 in | Driest |
| August | 63°F (17°C) | 2.1 in | Warmest |
| September | 58°F (15°C) | 2.8 in | |
| October | 53°F (12°C) | 3.4 in | |
| November | 46°F (8°C) | 3.7 in | Wettest |
| December | 43°F (6°C) | 3.6 in |
Portsmouth has a seasonal temperature swing of 23°F / from 40°F in January to 63°F in August. Total annual precipitation is 31.7 inches, with November being the wettest month (3.7") and July the driest (1.7").