December weather forecast
Rajagiriya, Sri Lanka

The first month of the winter, December, is also a moderately hot month in Rajagiriya, Sri Lanka, with an average temperature varying between 23.7°C (74.7°F) and 29.9°C (85.8°F).

Temperature

During December, Rajagiriya records an average high-temperature of a moderately hot 29.9°C (85.8°F), marking a slight divergence from November's 30.1°C (86.2°F). During December, the temperature tends to dip to an average of 23.7°C (74.7°F) at night.

Heat index

In December, the heat index is estimated at a fiery hot 37°C (98.6°F). Ensure extra safety measures, heat exhaustion and heat cramps are likely. Continuous activity might result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. A direct sunlight exposure may boost the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is a value derived by merging air temperature with the humidity to convey how the climate feels. The experience of temperature can be subjective, varying based on the individual's activity and heat perception, influenced by factors like wind, attire, and metabolic variations. Exposure to direct sun rays can influence the heat you feel, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Young ones often do not realize the necessity to rest and replenish their fluids. Thirst is a delayed indication of dehydration - keeping hydrated, particularly in prolonged physical activity, is crucial.
Humans rely on perspiration as a cooling mechanism, wherein the evaporating sweat counteracts excessive warmth. When air moisture content is high, the cooling process through evaporation is not as efficient, leading to an ineffective body cooling process and a feeling of overheating. When body temperature rises due to excess heat gain beyond its removal capability, one might experience heat-related disorders.

Humidity

In December, the average relative humidity in Rajagiriya is 79%.

Rainfall

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

Daylight

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

Sunshine

The average sunshine in December 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 in Rajagiriya. A UV Index estimate of 6 to 7 represents a high health risk from exposure to the Sun's UV radiation for average individuals.
Note: In December, a regular UV index of 7 translates into these guidelines:
Shun overexposure. Protection from sun ravages is indispensable. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage.