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

Weather in December

The first month of the summer, December, is still a warm month in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, with temperature in the range of an average low of 22°C (71.6°F) and an average high of 29°C (84.2°F).
The perfect water temperature of 25°C (77°F) with 4mm (0.16") of accumulated rainfall and only 1 rainfall days, makes December a great period for swimming and other water activities.

Temperature

In Ascension Island, the average high-temperature in December is almost the same as in November - a still warm 29°C (84.2°F). In Ascension Island, the average low-temperature is 22°C (71.6°F).

Heat index

In December, the average heat index is appraised at a hot 32.5°C (90.5°F). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like', 'apparent temperature', 'real feel', or 'felt air temperature', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (wind, metabolic differences, clothing). Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

In Ascension Island, the average relative humidity in December is 69%.

Rainfall

The months with the least rainfall in Ascension Island are January, November and December Rain falls for 1 days and accumulates 4mm (0.16") of rain.

Sea temperature

In Ascension Island, Saint Helena, Ascension and Tristan da Cunha, the average seawater temperature in December is 25°C (77°F).
Note: For swimming, diving, and other water activities, temperatures between 25°C (77°F) and 29°C (84.2°F) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

Daylight

With an average of 12h and 35min of daylight, December has the longest days of the year.
On the first day of December, sunrise is at 06:29 and sunset at 19:03. On the last day of the month, sunrise is at 06:43 and sunset at 19:17 GMT.

Sunshine

The average sunshine in December in Ascension Island 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 extreme health hazard from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 12 in December transform into the following instructions:
Practice all essential precautions. Protection against sun damage is crucial. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.
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FAQ

What is the temperature in December in Ascension Island?

The average high-temperature, in December, is 29°C (84.2°F), while the average low-temperature is 22°C (71.6°F). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which factors the actual air temperature with the relative humidity, in December is appraised at 32.5°C (90.5°F).

What is the average humidity in December in Ascension Island?

In Ascension Island, Saint Helena, Ascension and Tristan da Cunha, the average relative humidity in December is 69%.

What is the driest month in Ascension Island?

The months with the least rainfall in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, are January, November and December Rain falls for 1 days and accumulates 4mm (0.16") of rain.

How much does it rain in Ascension Island in December?

In Ascension Island, Saint Helena, Ascension and Tristan da Cunha, in December, during 1 rainfall days, 4mm (0.16") of precipitation is typically accumulated.

What is the sea water temperature in December in Ascension Island?

In Ascension Island, Saint Helena, Ascension and Tristan da Cunha, in December, the average water temperature is 25°C (77°F). For swimming, diving, and other water activities, temperatures between 25°C (77°F) and 29°C (84.2°F) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

When are the longest days in Ascension Island?

The month with the longest days in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, is December, with an average of 12h and 35min of daylight.

How many hours of daylight does Ascension Island have in December?

In December, the average day length in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, is 12h and 35min.

What time are sunrise and sunset in December in Ascension Island?

On the first day of December in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, sunrise is at 06:29 and sunset at 19:03. On the last day of the month, sunrise is at 06:43 and sunset at 19:17 GMT.

How long on average sun shines in December in Ascension Island?

The average sunshine duration in December in Ascension Island, Saint Helena, Ascension and Tristan da Cunha, is 6.4h.

What is the month with the highest UV index in Ascension Island?

The months with the highest UV index are January through April, September through December, with an average maximum UV index of 12.

What is the UV index reading in December in Ascension Island?

In December, the average daily maximum UV index in Ascension Island is 12. A UV Index estimate of 11, and higher, represents an excessive health risk from unsafe exposure to Sun's UV rays.

Average temperature in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average temperature in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average high temperature in December: 29°C

The warmest months (with the highest average high temperature) are February, March, April and May (31°C).
The months with the lowest average high temperature are August, September, October and November (28°C).

  • Average low temperature in December: 22°C

The months with the highest average low temperature are March, April and May (24°C).
The coldest months (with the lowest average low temperature) are July, August, September, October, November and December (22°C).

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Average humidity in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average humidity in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average humidity in December: 69%

The month with the highest relative humidity is January (70%).
The month with the lowest relative humidity is July (67%).

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Average rainfall in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average rainfall in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average rainfall in December: 4mm

The wettest month (with the highest rainfall) is April (33mm).
The driest months (with the least rainfall) are January, November and December (4mm).

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Average rainfall days in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average rainfall days in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average rainfall days in December: 1 days

The month with the highest number of rainy days is April (4 days).
The months with the least rainy days are November and December (1 days).

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Average sea temperature in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average sea temperature in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average sea temperature in December: 25°C

The best months for swimming (with the highest average sea temperature) are March, April and May (28°C).
The coldest months (with the lowest average sea temperature) are September and October (24°C).

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Average daylight in December /
Average sunshine in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average daylight in December / Average sunshine in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average daylight in December: 12h and 35min

The month with the longest days is December (Average daylight: 12h and 35min).
The month with the shortest days is June (Average daylight: 11h and 40min).

  • Average sunshine in December: 6.4h

The months with the most sunshine are March and April (Average sunshine: 8.9h).
The month with the least sunshine is October (Average sunshine: 5.2h).

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Average UV index in December
Ascension Island, Saint Helena, Ascension and Tristan da Cunha

Average UV index in December - Ascension Island, Saint Helena, Ascension and Tristan da Cunha
  • Average UV index in December: 12

The months with the highest UV index are January, February, March, April, September, October, November and December (UV index 12).
The months with the lowest UV index are June and July (UV index 9).

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