Monthly weather forecast and climate
Alderney, Guernsey

Weather in January

In Alderney, Guernsey, in January, the average water temperature is 10.1°C (50.2°F). Note: Swimming in 10.1°C (50.2°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in January »

Weather in February

In Alderney, Guernsey, the average seawater temperature in February is 9.7°C (49.5°F). Note: Swimming in 9.7°C (49.5°F) is considered life-threatening. Weather in February »

Weather in March

With an average sea temperature of 9.3°C (48.7°F), March is the month with the coldest seawater in Alderney, Guernsey. Note: Swimming in 9.3°C (48.7°F) is considered dangerous. Weather in March »

Weather in April

In Alderney, Guernsey, the average seawater temperature in April is 10.3°C (50.5°F). Note: Swimming in 10.3°C (50.5°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in April »

Weather in May

In Alderney, Guernsey, in May, the average water temperature is 11.8°C (53.2°F). Note: Swimming in 11.8°C (53.2°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in May »

Weather in June

In Alderney, Guernsey, the average seawater temperature in June is 13.8°C (56.8°F). Note: Swimming in 13.8°C (56.8°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 Alderney, Guernsey, the average seawater temperature in July is 15.7°C (60.3°F). Note: Swimming in 15.7°C (60.3°F) is not enjoyable for the majority. Weather in July »

Weather in August

In Alderney, Guernsey, the average seawater temperature in August is 17.2°C (63°F). Note: For most, swimming in 17.2°C (63°F) is not an enjoyable activity. Weather in August »

Weather in September

September is the month with the warmest seawater in Alderney, Guernsey, with an average sea temperature of 17.4°C (63.3°F). Note: For most, swimming in 17.4°C (63.3°F) is not an enjoyable activity. Weather in September »

Weather in October

In Alderney, Guernsey, the average seawater temperature in October is 16.3°C (61.3°F). Note: For most, swimming in 16.3°C (61.3°F) is not an enjoyable activity. Weather in October »

Weather in November

In November, the average sea temperature in Alderney, Guernsey, is 14.5°C (58.1°F). Note: Swimming in 14.5°C (58.1°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation. Weather in November »

Weather in December

In December, the average sea temperature in Alderney, Guernsey, is 12°C (53.6°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 December »
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FAQ

What is the month with the coldest sea water in Alderney?

With an average sea temperature of 9.3°C (48.7°F), March is the month with the coldest seawater in Alderney, Guernsey.

When are the longest days in Alderney?

With an average of 16.2h of daylight, June has the longest days of the year in Alderney, Guernsey.

What is the month with the warmest sea water in Alderney?

The month with the warmest seawater in Alderney is September, with an average sea temperature of 17.4°C (63.3°F).

What is the month with the shortest days in Alderney?

With an average of 8.2h of daylight, December has the shortest days of the year in Alderney.

Average sea temperature
Alderney, Guernsey

Average sea temperature - Alderney, Guernsey

The best month for swimming (with the highest average sea temperature) is September (17.4°C).
The coldest month (with the lowest average sea temperature) is March (9.3°C).

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Average daylight
Alderney, Guernsey

Average daylight - Alderney, Guernsey

The month with the longest days is June (Average daylight: 16.2h).
The month with the shortest days is December (Average daylight: 8.2h).

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