Monthly weather forecast and climate
Naantali, Finland

Weather in January

In January, the average sea temperature in Naantali, Finland, is 0.7°C (33.3°F). Note: For swimming, this is considered life-threatening and very dangerous. Weather in January »

Weather in February

February is the month with the coldest seawater in Naantali, Finland, with an average sea temperature of -0.4°C (31.3°F). Note: For swimming, this is considered extremely cold, dangerous, and life-threatening. Weather in February »

Weather in March

In Naantali, Finland, in March, the average water temperature is -0.3°C (31.5°F). Note: For swimming, this is considered life-threatening and very dangerous. Weather in March »

Weather in April

In Naantali, Finland, in April, the average water temperature is 0.5°C (32.9°F). Note: For swimming, this is considered very dangerous and immediately life-threatening. Weather in April »

Weather in May

In Naantali, Finland, in May, the average water temperature is 3.8°C (38.8°F). Note: For swimming, this is considered extremely cold, dangerous, and life-threatening. Weather in May »

Weather in June

In Naantali, Finland, the average seawater temperature in June is 8.9°C (48°F). Note: Swimming in 8.9°C (48°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in June »

Weather in July

In July, the average sea temperature in Naantali, Finland, is 12.4°C (54.3°F). Note: At temperatures below 10°C (50°F), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Weather in July »

Weather in August

August is the month with the warmest seawater in Naantali, Finland, with an average sea temperature of 12.8°C (55°F). Note: Swimming in 12.8°C (55°F) is considered dangerous. Weather in August »

Weather in September

In Naantali, Finland, in September, the average water temperature is 10.3°C (50.5°F). Note: At temperatures below 10°C (50°F), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Weather in September »

Weather in October

In Naantali, Finland, in October, the average water temperature is 6.6°C (43.9°F). Note: Swimming in 6.6°C (43.9°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in October »

Weather in November

In Naantali, Finland, in November, the average water temperature is 4.3°C (39.7°F). Note: For swimming, this is considered life-threatening and very dangerous. Weather in November »

Weather in December

In December, the average sea temperature in Naantali, Finland, is 2.1°C (35.8°F). Note: For swimming, this is considered extremely cold, dangerous, and life-threatening. Weather in December »
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FAQ

What month is the sea coldest in Naantali?

The month with the coldest seawater in Naantali, Finland, is February, with an average sea temperature of -0.4°C (31.3°F).

When are the longest days in Naantali?

With an average of 18.9h of daylight, June has the longest days of the year in Naantali, Finland.

When is the sea warmest in Naantali?

August is the month with the warmest seawater, with an average sea temperature of 12.8°C (55°F).

What is the month with the shortest days in Naantali?

The month with the shortest days is December, with an average of 5.9h of daylight.

Average sea temperature
Naantali, Finland

Average sea temperature - Naantali, Finland

The best month for swimming (with the highest average sea temperature) is August (12.8°C).
The coldest month (with the lowest average sea temperature) is February (-0.4°C).

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Average daylight
Naantali, Finland

Average daylight - Naantali, Finland

The month with the longest days is June (Average daylight: 18.9h).
The month with the shortest days is December (Average daylight: 5.9h).

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