December weather forecast
Colombo, Sri Lanka

Closing the year, December in Colombo features the most significant decrease in rainfall to 148mm (5.83"). The relative humidity matches November levels, keeping the moisture in the air fairly consistent. The wind picks up just slightly, providing a comfortable, gentle breeze. Daylight hours slightly recede to match January’s level. The city's festive atmosphere, combined with comfortable weather conditions, makes this a delightful month to conclude the year in Colombo.

Temperature

Colombo's average high-temperature in December is a moderately hot 29.9°C (85.8°F), marking an insignificant difference from the 30.1°C (86.2°F) of November. During December, Colombo experiences an average low-temperature of 23.7°C (74.7°F) at night.

Heat index

For December, the heat index is computed to be a very hot 37°C (98.6°F). Apply extra caution, heat cramps and heat exhaustion could happen. Heatstroke might occur with long-duration activity.
In terms of the heat index, values are set with light wind and shade conditions in mind. The heat index might be elevated by 15 Fahrenheit (8 Celsius) degrees due to direct sun exposure.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', quantifies the warmth felt when relative humidity is considered. Additional elements encompassing metabolic differences, the degree of physical activity, and attire can impact the individual's perception of temperature. Take note that direct exposure to the sun can increase the felt temperature, possibly adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values hold particular significance for children. Kids often lack the knowledge about the necessity to take breaks and consume liquids. Thirst, as a late symptom of dehydration, necessitates the maintenance of hydration, particularly during enduring physical activities.
One way the human body deals with excessive warmth is by perspiring and allowing sweat to evaporate. Heightened relative humidity interferes with the body's usual cooling mechanism by reducing evaporation, subsequently decreasing the body's cooling rate and increasing the sensation of heat. Rising body temperatures resulting from an imbalance in heat absorption can lead to potential thermal issues.

Humidity

In December, the average relative humidity is 79%.

Rainfall

In Colombo, in December, it is raining for 21.1 days, with typically 148mm (5.83") of accumulated precipitation. Throughout the year, there are 289.4 rainfall days, and 2262mm (89.06") of precipitation is accumulated.

Sea temperature

In Colombo, in December, the average water temperature is 28.1°C (82.6°F).
Note: For swimming, diving, or other water activities, temperatures from 25°C (77°F) to 29°C (84.2°F) provide the most enjoyable experience for extended periods without discomfort.

Daylight

December has the shortest days of the year, with an average of 11h and 42min of daylight.
On the first day of December, sunrise is at 06:07 and sunset at 17:52. On the last day of the month, sunrise is at 06:21 and sunset at 18:05 +0530.

Sunshine

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

UV index

The months with the highest UV index in Colombo are January through April, July, September, November and December, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: The maximum daily UV index of 7 in December converts into the following recommendations:
Sustain precautions and conform to sun safety norms. Preventing sunburn is necessary. Stay in the shade and limit direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is particularly strong. Remember, however, that shade structures may not provide complete protection. Boost your sun resistance with garments that are densely woven yet spacious. Warning! Sand and water reflections boost the intensity of UV exposure.