December weather forecast
Polonnaruwa, Sri Lanka

December, the first month of the winter in Polonnaruwa, is still a warm month, with an average temperature fluctuating between 29.3°C (84.7°F) and 21.4°C (70.5°F).

Temperature

January and December, with an average high-temperature of 29.3°C (84.7°F), are the coldest months.

Heat index

In December, the average heat index is computed to be a torrid 37°C (98.6°F). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. 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', 'felt air temperature', 'real feel', or 'apparent temperature', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like activity, clothing, metabolic differences, and wind affect individual temperature impact. 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. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
Perspiration is the human body's physiological response to high temperatures and is an attempt to lower body temperature through 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

With an average relative humidity of 84%, December is the most humid month.

Rainfall

In Polonnaruwa, during December, the rain falls for 22.9 days and regularly aggregates up to 127mm (5") of precipitation. In Polonnaruwa, during the entire year, the rain falls for 196.8 days and collects up to 943mm (37.13") of precipitation.

Daylight

December has the shortest days of the year in Polonnaruwa, with an average of 11h and 40min of daylight.
On the first day of December in Polonnaruwa, sunrise is at 06:03 and sunset at 17:45. On the last day of the month, sunrise is at 06:18 and sunset at 17:58 +0530.

Sunshine

The month with the least sunshine is December, with an average of 4.9h of sunshine.

UV index

The months with the lowest UV index are January, November and December, with an average maximum UV index of 6. A UV Index estimate of 6 to 7 represents a high health hazard from exposure to the Sun's UV radiation for ordinary individuals.
Note: In December, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. 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. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.