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Weather & Climate in St Mary's, United Kingdom
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St Mary's experiences four distinct seasons with an average annual temperature of 53°F (12°C). Winters average 48°F in January while summers reach 61°F in July / relatively mild seasonal variation. The area gets 263 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 40.3 inches. The city sits at an elevation of 46 feet.
Temperature
48°F Jan (9°C)
61°F Jul (16°C)
| Annual Average | 53.2°F |
| 1% below US avg | |
| January Average | 48°F (9°C) |
| July Average | 61°F (16°C) |
| Sunny Days | 263 days/yr |
Geography
| Elevation | 46 ft (14 m) |
| Area | 2.4 sq mi (6.3 km²) |
| Population Density | 686/sq mi |
| Coordinates | 49.9172°N, 6.2952°W |
| Timezone | Europe/London |
Precipitation & Snow
Air Quality
Earthquake History
8 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.1.
| Nov 10, 1996 | 19 km S of St Just, United Kingdom | M4.1 | 48 km | 10 km |
| Oct 14, 2002 | 98 km S of Hugh Town, United Kingdom | M3.3 | 99 km | 10 km |
| Jun 29, 1992 | 121 km WSW of Hugh Town, United Kingdom | M3.2 | 123 km | 10 km |
| Jan 19, 2001 | 53 km S of Mullion, United Kingdom | M3.2 | 95 km | 10 km |
| Mar 28, 2005 | 71 km WNW of Porspoder, France | M3.0 | 128 km | 10 km |
| Feb 8, 1998 | 18 km SW of Mullion, United Kingdom | M2.9 | 62 km | 5 km |
| Mar 23, 2008 | 38 km NW of St Just, United Kingdom | M2.8 | 55 km | 6 km |
| Apr 2, 2000 | 33 km S of Mullion, United Kingdom | M2.7 | 83 km | 10 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 48°F (9°C) | 5.0 in | Wettest |
| February | 47°F (8°C) | 3.9 in | Coldest |
| March | 48°F (9°C) | 3.4 in | |
| April | 49°F (10°C) | 2.2 in | |
| May | 53°F (12°C) | 2.3 in | |
| June | 58°F (14°C) | 2.2 in | |
| July | 61°F (16°C) | 2.0 in | Driest |
| August | 61°F (16°C) | 2.8 in | Warmest |
| September | 59°F (15°C) | 3.4 in | |
| October | 55°F (13°C) | 4.0 in | |
| November | 51°F (11°C) | 4.4 in | |
| December | 49°F (9°C) | 4.8 in |
St Mary's has a seasonal temperature swing of 15°F / from 47°F in February to 61°F in August. Total annual precipitation is 40.3 inches, with January being the wettest month (5.0") and July the driest (2.0").