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

Ushering in the end of the year, December maintains the calm weather noted in November. Daytime temperatures hover around 29°C (84.2°F) and decrease to 22°C (71.6°F) during nights. A mere 4mm (0.16") of rainfall is measured, resulting in more sun-filled days. The Island bustles with cheer and the weather lends itself perfectly for all kinds of festivities. The transition to a new year with January brings back the slightly warmer days of summer.

Temperature

Ascension Island experiences a transition to a still warm 29°C (84.2°F) in average high-temperatures with the arrival of December, not greatly differing from November's 28°C (82.4°F). In Ascension Island, an average temperature of 22°C (71.6°F) is noted during December nights.

Heat index

During December, the heat index is calculated to be a tropical 33°C (91.4°F). Emphasize additional safety, risk of heat cramps and heat exhaustion is high. Continuous activity might result in heatstroke.
When referencing the heat index, its values are suitable for shady environments and light breezes. The heat index may experience an enhancement of 15 Fahrenheit (8 Celsius) degrees under direct sunlight.
Note: The heat index, also known as 'felt air temperature' or 'feels like', binds temperature metrics with humidity values to give a sense of the actual warmth. One's perception of temperature can vary depending on physical activity and individual heat sensitivity, influenced by factors like wind, attire, and metabolic variations. Given the impact of direct sunlight, it's noteworthy that the felt temperature can rise by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children frequently underestimate the importance of resting and drinking fluids. Thirst is a symptom of advanced dehydration - hence the need to hydrate regularly, especially during protracted physical exercises.

Humidity

In December, the average relative humidity is 69%.

Rainfall

January, November and December are months with the least rain in Ascension Island when the rain falls for 1 days and typically aggregates up to 4mm (0.16") of rain.

Sea temperature

In Ascension Island, in December, the average water temperature is 25°C (77°F).
Note: For any water activity, having surface water temperatures from 25°C (77°F) to 29°C (84.2°F) is considered outstanding and highly delightful for lengthened periods.

Daylight

December has the longest days of the year in Ascension Island, with an average of 12h and 36min of daylight.
On the first day of December, sunrise is at 06:30 and sunset at 19:03. On the last day of the month, sunrise is at 06:43 and sunset at 19:18 GMT.

Sunshine

The average sunshine in December is 6.4h.

UV index

The months with the highest UV index are January through April, September through December, with an average maximum UV index of 12. A UV Index reading of 11, and higher, represents an ultimate health vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum UV index, 12 during December, leads to the following recommendations:
Execute all crucial precautions. Warding off sun exposure is non-negotiable. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Sunscreen with a sun protection factor of no less than 30 should be used liberally and reapplied frequently on overcast days, including after every swim or outdoor activity. Be vigilant! The Sun's UV rays get a boost from sand and water reflections.