December weather forecast
Colombo, Sri Lanka

December, the first month of the winter in Colombo, is also a moderately hot month, with an average temperature ranging between min 23.7°C (74.7°F) and max 29.9°C (85.8°F).

Temperature

In Colombo, Sri Lanka, the average high-temperature in December is practically the same as in November - a moderately hot 29.9°C (85.8°F). The average low-temperature, in December, is 23.7°C (74.7°F).

Heat index

The average heat index in December is estimated at a sweltering 37°C (98.6°F). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'apparent temperature', 'real feel', or 'feels like', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (pregnancy, differences in body mass, height, and shape, clothing). Bear in mind that direct sunshine exposure increases weather impact, and may raise 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.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. When the relative humidity is high, the evaporation rate is reduced. The warmth is removed from the body at a lower rate, causing the body to retain more heat than it would in dry air. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 37.5°C (99.5°F) to 38.3°C (100.9°F), thermal conditions are potentially life-threatening.

Humidity

The average relative humidity in December in Colombo is 79%.

Rainfall

In December, the rain falls for 21.1 days. Throughout December, 148mm (5.83") of precipitation is accumulated. In Colombo, during the entire year, the rain falls for 289.4 days and collects up to 2262mm (89.06") of precipitation.

Sea temperature

In Colombo, the average water temperature is 28.1°C (82.6°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 11h and 44min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 06:06 and sunset at 17:51. On the last day of December, in Colombo, sunrise is at 06:21 and sunset at 18:05 +0530.

Sunshine

In December, the average sunshine in Colombo is 6.9h.

UV index

January through April, July, September, November and December, with an average maximum UV index of 7, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high health hazard from unprotected exposure to Sun's UV rays for average individuals.
Note: The average daily UV index of 7 in December transform into the following instructions:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. 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. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.