World sea water temperatures

Water temperature in St Mary's

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This data the coastal St Mary's sea water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.

Current sea temperature in St Mary's

Water temperature in St Mary's today is 16.9°C. Based on our historical data over a period of ten years, the warmest water in this day in the Celtic Sea near St Mary's was recorded in 2013 and was 17.5°C, and the coldest was recorded in 2008 at 15°C. Sea water temperature in St Mary's is expected to drop to 16.1°C in the next 10 days. September average water temperature in St Mary's is 15.9°C, the minimum temperature is 14°C, and the maximum is 18.7°C.

Throughout the year, the water temperature in St Mary's does not rise above 20°C and therefore is not suitable for comfortable swimming. The average water temperature in St Mary's in winter reaches 10.8°C, in spring 10.8°C, in summer the average temperature rises to 15.9°C, and in autumn it is 14.3°C.

St Mary's water temperature now


5 September 2025
today temp
16.9°C
4 September 2025
yesterday temp
17.2°C


The sea salinity in St Mary's is 35.00‰, and the average salinity of the World Ocean is 35‰.

Surf Forecast in St Mary's for today

Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for St Mary's. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast St Mary's. Data in table shown for 5 September 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)

0-3 h3-6 h6-9 h9-12 h
6' 7"6' 0"5' 6"5' 1"
2.01 m1.84 m1.68 m1.55 m
12-15 h15-18 h18-21 h21-24 h
4' 9"4' 7"4' 7"4' 9"
1.46 m1.4 m1.39 m1.44 m

Surf report in St Mary's

St Mary's wave height and direction

St Mary's weather forecast

St Mary's wind speed and direction

Current temperature and weather

Data in a table show St Mary's temperature today (5 September 2025). For more information and forecast for a few days, go to the weather forecast St Mary's.

0-3 h3-6 h6-9 h9-12 h
16.8°C16.7°C16.7°C16.8°C
12-15 h15-18 h18-21 h21-24 h
16.9°C17°C17.1°C17.1°C

You may also be interested in other sections of our site for St Mary's: Sunrise and Sunset, Tides

St Mary's water temperature by month

These figures shows the average, minimum and maximum monthly sea temperature in St Mary's. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in St Mary's on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve

MonthAvrMinMax
January10.7°C9.4°C11.9°Ccold
Sea water temperature in St Mary's in January
February10°C9°C10.9°Ccold
Sea water temperature in St Mary's in February
March9.9°C8.7°C11.1°Ccold
Sea water temperature in St Mary's in March
April10.5°C9.1°C12.5°Ccold
Sea water temperature in St Mary's in April
May12.1°C10.1°C15.3°Ccold
Sea water temperature in St Mary's in May
June14.5°C11.7°C17.8°Ccold
Sea water temperature in St Mary's in June
July16.4°C13.6°C19.8°Ccold
Sea water temperature in St Mary's in July
August16.8°C14.9°C19.6°Ccold
Sea water temperature in St Mary's in August
September15.9°C14°C18.7°Ccold
Sea water temperature in St Mary's in September
October14.3°C12.6°C16.4°Ccold
Sea water temperature in St Mary's in October
November12.8°C11.3°C14.3°Ccold
Sea water temperature in St Mary's in November
December11.6°C10°C13°Ccold
Sea water temperature in St Mary's in December

Chart monthly average water temperature in St Mary's

Water temperature in St Mary's

Where is the warmest sea water in the world?

If you want to plan a vacation on the beach and enjoy the warm sea, choose the day of the year, region and the minimum comfortable sea/ocean temperature that interests you. As a result, you will get a list of countries and cities in which the average sea temperature or maximum temperature on this day over the past 10 years exceeds your chosen value

Region
Date (day and month)
Water temperature: min 16°C
 Average temperature  Maximum temperature

Nearby beaches and cities

The nearest beaches and cities from St Mary's with the water temperature today, as well as the air temperature and the state of the weather during the day and the average wave height for today

WaterWeatherWave
Land's End16.4°C17°C1.52 m
Saint Just16.2°C17°C1.39 m
Sennen16.2°C17°C1.39 m
Sennen Cove16.3°C17°C1.39 m
Porthcurno16.5°C17°C1.5 m
Mousehole16.7°C17°C1.08 m
Newlyn16.7°C17°C1.08 m
Porthmeor16.7°C17°C1.2 m
Penzance16.6°C17°C1.08 m
Marazion16.6°C17°C1.08 m

Cornwall photo gallery

  • Cornwall
  • Sunrise over the National Coastwatch Institutions Station
  • Cornwall
  • Polperro from the coast path

If you have interesting photos of this place, you can upload them here. Photos will be available to all users after verification by the moderator.

Other names for St Mary's

St. Mary's, St Marys, St. Marys

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[1] - The "Blue Flag" is awarded to beaches which fulfill a number of criteria, including: the quality of the bathing water, which must be in accordance with the relevant European Union Directive environmental education and information and beach area management and safety.

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Our report for St Mary's is compiled using satellite data together with in-situ observations to get the most reliable daily data of sea surface temperatures, surf forecasts, current temperatures and weather forecasts.

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