St Mary's Bay Sea Water Temperature
A temperate beach on the Celtic Sea, warmest around August at about 16.6°C. Today's reading, 7-day forecast, and monthly averages below.
St Mary's Bay water temperature
Invigorating and crisp. Tolerable for active swimming, but chilly for prolonged casual bathing.
7-Day Water Temperature Forecast
St Mary's Bay Monthly Water Temperature Averages
Historical monthly climatology. The warmest water in St Mary's Bay occurs inJuly, August, September, October — peaking at16.6°C (61.9°F) in August.
Year-Round Water Temperature Curve (°C / °F)
Hover a bar for detailsFull 12-month data table — min / avg / max & swimming comfort
| Month | Min Water Temp | Average Water Temp | Max Water Temp | Swimming Comfort |
|---|---|---|---|---|
| January | 8.4°C | 10.3°C | 11.7°C | Very Cold (< 16°C) |
| February | 8.1°C | 9.5°C | 11°C | Very Cold (< 16°C) |
| March | 7.3°C | 9°C | 10.1°C | Very Cold (< 16°C) |
| April | 8.6°C | 9.9°C | 11.4°C | Very Cold (< 16°C) |
| May | 9.8°C | 11.7°C | 14.5°C | Very Cold (< 16°C) |
| June | 11.9°C | 13.9°C | 16.3°C | Very Cold (< 16°C) |
| July | 13.4°C | 15.7°C | 18°C | Very Cold (< 16°C) |
| August | 15.3°C | 16.6°C | 19.4°C | Cool / Refreshing (16°C – 20°C) |
| SeptemberCurrent | 15.5°C | 16.6°C | 17.9°C | Cool / Refreshing (16°C – 20°C) |
| October | 14°C | 15.7°C | 17.1°C | Very Cold (< 16°C) |
| November | 10.8°C | 13.7°C | 16.1°C | Very Cold (< 16°C) |
| December | 10°C | 11.6°C | 13.2°C | Very Cold (< 16°C) |
Swimming FAQs for St Mary's Bay
Is the sea warm enough to swim in St Mary's Bay today?
Typical sea surface temperature in St Mary's Bay this time of year is 16.6°C (61.9°F) — classified as Cool / Refreshing (16°C – 20°C). Invigorating and crisp. Tolerable for active swimming, but chilly for prolonged casual bathing. Live readings load automatically.
What are the warmest months for swimming in St Mary's Bay?
The highest water temperatures in St Mary's Bay typically occur duringJuly, August, September, October, when monthly averages reach peak seasonal levels.
What is the typical water temperature in St Mary's Bay in September?
Historically in September, water temperatures in St Mary's Bay average around16.6°C (61.9°F), fluctuating between a recorded minimum of 15.5°C and a maximum of 17.9°C.