St. Mary's, Isles of Scilly weather by month & the best time to visit
United Kingdom · seaside town · oceanic / maritime climate
The best time to visit St. Mary's, Isles of Scilly is August — its sunniest month (Sunshine Score 58/100), with July and September close behind. St. Mary's, Isles of Scilly averages about 1,869 hours of sunshine a year. Daytime highs around 17°C / 63°F and roughly 70 mm of rain in August.
When is the best time to visit St. Mary's, Isles of Scilly?
For sunshine, the best time to visit St. Mary's, Isles of Scilly is August, then July and September. The dullest month is January (12/100, 107 mm of rain). The full month-by-month picture is in the table below.
How sunny is St. Mary's, Isles of Scilly?
St. Mary's, Isles of Scilly gets a moderate 1,869 hours of sunshine a year. 46 Sunshine Score points separate August (58) from January (12), so the month you pick matters. It ranks #3 of 48 destinations in United Kingdom for annual sunshine, above the national median of 1,345 hours. The year's 1,006 mm of rain spreads fairly evenly across the months, with no pronounced dry season.
Sunshine Score by month
| Month | Score | Day high | Night low | Rain | UV | Sea |
|---|---|---|---|---|---|---|
| January | 12 | 10° / 50°F | 9° / 48°F | 107 mm | 0 | 11° / 52°F |
| February | 12 | 10° / 50°F | 8° / 46°F | 87 mm | 1 | 11° / 52°F |
| March | 12 | 10° / 50°F | 8° / 46°F | 81 mm | 2 | 11° / 52°F |
| April | 19 | 11° / 52°F | 9° / 48°F | 64 mm | 4 | 11° / 52°F |
| May | 26 | 12° / 54°F | 11° / 52°F | 63 mm | 5 | 14° / 57°F |
| June | 45 | 15° / 59°F | 14° / 57°F | 63 mm | 6 | 15° / 59°F |
| July | 57 | 17° / 63°F | 16° / 61°F | 77 mm | 6 | 16° / 61°F |
| August | 58 | 17° / 63°F | 16° / 61°F | 70 mm | 5 | 17° / 63°F |
| September | 52 | 16° / 61°F | 15° / 59°F | 64 mm | 4 | 16° / 61°F |
| October | 35 | 14° / 57°F | 13° / 55°F | 105 mm | 2 | 14° / 57°F |
| November | 23 | 12° / 54°F | 11° / 52°F | 112 mm | 1 | 14° / 57°F |
| December | 17 | 11° / 52°F | 10° / 50°F | 113 mm | 0 | 12° / 54°F |
Sea temperature in St. Mary's, Isles of Scilly by month
The sea off St. Mary's, Isles of Scilly is warmest in August at around 17°C / 63°F, and coolest in January at 11°C / 52°F. It never reaches comfortable swimming temperatures (21°C+). Month-by-month sea-surface temperatures are in the Sea column of the table above.
Nearest destinations
St. Mary's, Isles of Scilly: questions and answers
What kind of destination is St. Mary's, Isles of Scilly?
St. Mary's, Isles of Scilly is a seaside town in United Kingdom with a oceanic / maritime climate — the sea reaches 17°C at its warmest.
How many hours of sunshine does St. Mary's, Isles of Scilly get a year?
St. Mary's, Isles of Scilly gets about 1,869 hours of sunshine a year, at its best around August.
When is the best time to visit St. Mary's, Isles of Scilly?
The sunniest time to visit St. Mary's, Isles of Scilly is August, when the Sunshine Score peaks at 58/100 (with July and September close behind). Expect daytime highs around 17°C / 63°F.
What is the least sunny month in St. Mary's, Isles of Scilly?
January is the least sunny month in St. Mary's, Isles of Scilly, scoring 12/100 with about 107 mm of rain.
What is the sea temperature in St. Mary's, Isles of Scilly?
The sea in St. Mary's, Isles of Scilly ranges from about 11°C (January) to 17°C (August). Month-by-month sea temperatures are on this page.
How strong is the sun in St. Mary's, Isles of Scilly?
The typical midday UV index in St. Mary's, Isles of Scilly peaks around 6 (high) in June, easing to about 0 (low) in January. Month-by-month midday UV values are in the UV column of the table on this page.
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