December weather forecast
Saint Helena Island, Saint Helena, Ascension and Tristan da Cunha

December wraps up the weather cycle in Saint Helena Island, Ascension and Tristan da Cunha, marking a return to hotter temperatures. The weather remains warm and balmy, making for perfect beach days. Sea temperatures rise further to 22°C (71.6°F), creating an inviting setting for water sports and swimming. On a cautionary note, there is an evident increase in rainfall to 37mm (1.46") during December. Summarily, the vibrant and versatile climate of December guarantees an enjoyable holiday experience for all globe-trotters and inhabitants alike.

Temperature

The average high-temperature during December registers at a pleasant 20°C (68°F), maintaining a close resemblance to the previous month. Saint Helena Island documents a consistent average low-temperature of 16°C (60.8°F) at night during December.

Rainfall

In Saint Helena Island, in December, during 12 rainfall days, 37mm (1.46") of precipitation is typically accumulated. Throughout the year, in Saint Helena Island, there are 170 rainfall days, and 748mm (29.45") of precipitation is accumulated.

Sea temperature

In December, the average sea temperature in Saint Helena Island is 22°C (71.6°F).
Note: For those with a heightened sensitivity to cold, sunshine, wind, and outside temperature make a big difference in enjoying a swim at 22°C (71.6°F). (Olympic swimming regulations state a water temperature of 25°C (77°F) to 28°C (82.4°F).)

Daylight

With an average of 13h and 6min of daylight, December has the longest days of the year.
On the first day of December in Saint Helena Island, sunrise is at 05:41 and sunset at 18:42. On the last day of the month, sunrise is at 05:54 and sunset at 18:57 GMT.

Sunshine

September and December, with an average of 12h of sunshine, are months with the least sunshine.

UV index

January through March, October through December, with an average maximum UV index of 12, are months with the highest UV index. A UV Index reading of 11, and higher, represents an extreme threat to health from exposure to the Sun's UV radiation for the average person.
Note: The maximum daily UV index of 12 in December converts into the following recommendations:
Adopt all important safety measures, unprotected skin may burn rapidly. Between 10 a.m. and 4 p.m., the Sun's UV radiation is at its peak. Limit your exposure to direct sunlight during these hours. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Limit direct sunlight exposure, particularly if you burn easily. It’s crucial to apply sunscreen with a minimum 30 SPF. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.