This data the coastal Riantec 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.
Water temperature in Riantec today is 18.2°C. Based on our historical data over a period of ten years, the warmest water in this day in Riantec was recorded in 2022 and was 18.9°C, and the coldest was recorded in 2008 at 16.5°C. Sea water temperature in Riantec is expected to drop to 17.3°C in the next 10 days. September average water temperature in Riantec is 17.2°C, the minimum temperature is 15°C, and the maximum is 19.4°C.
Throughout the year, the water temperature in Riantec does not rise above 20°C and therefore is not suitable for comfortable swimming. But on some days of July, the water temperature warms up to 20°C and above. The average water temperature in Riantec in winter reaches 10.3°C, in spring 12°C, in summer the average temperature rises to 17.4°C, and in autumn it is 15.6°C.
5 September 2025 |
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today temp |
18.2°C |
4 September 2025 |
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yesterday temp |
18.4°C |
The sea salinity in Riantec is 34.52‰, and the average salinity of the World Ocean is 35‰.
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 Riantec. 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 Riantec. Data in table shown for 6 September 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)
0-3 h | 3-6 h | 6-9 h | 9-12 h |
---|---|---|---|
4' 3" | 3' 10" | 3' 5" | 3' 2" |
1.29 m | 1.16 m | 1.05 m | 0.96 m |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
2' 11" | 2' 7" | 2' 5" | 2' 2" |
0.88 m | 0.8 m | 0.73 m | 0.67 m |
Data in a table show Riantec temperature today (6 September 2025). For more information and forecast for a few days, go to the weather forecast Riantec.
0-3 h | 3-6 h | 6-9 h | 9-12 h |
---|---|---|---|
![]() | ![]() | ![]() | ![]() |
13.6°C | 12.9°C | 12.4°C | 16.2°C |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
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19.2°C | 19.1°C | 17.9°C | 14.1°C |
You may also be interested in other sections of our site for Riantec: Sunrise and Sunset, Tides
These figures shows the average, minimum and maximum monthly sea temperature in Riantec. 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 Riantec 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
Month | Avr | Min | Max | |
---|---|---|---|---|
January | 10°C | 7°C | 12.4°C | cold |
Sea water temperature in Riantec in January | ||||
February | 9.5°C | 7.8°C | 11.1°C | cold |
Sea water temperature in Riantec in February | ||||
March | 10°C | 7.6°C | 12°C | cold |
Sea water temperature in Riantec in March | ||||
April | 11.9°C | 8.6°C | 15.6°C | cold |
Sea water temperature in Riantec in April | ||||
May | 14°C | 11.3°C | 17.4°C | cold |
Sea water temperature in Riantec in May | ||||
June | 16.4°C | 13.1°C | 19.7°C | cold |
Sea water temperature in Riantec in June | ||||
July | 17.7°C | 15.3°C | 20.3°C | cold |
Sea water temperature in Riantec in July | ||||
August | 18.1°C | 15.6°C | 20.4°C | cold |
Sea water temperature in Riantec in August | ||||
September | 17.2°C | 15°C | 19.4°C | cold |
Sea water temperature in Riantec in September | ||||
October | 15.8°C | 12.8°C | 18.9°C | cold |
Sea water temperature in Riantec in October | ||||
November | 13.7°C | 11.2°C | 16.6°C | cold |
Sea water temperature in Riantec in November | ||||
December | 11.5°C | 9.3°C | 14.4°C | cold |
Sea water temperature in Riantec in December |