December weather forecast
Unawatuna, Sri Lanka

As the last month of the year, December's weather in Unawatuna maintains a pleasing equilibrium of rain and sunshine. The average wind speed drops to 9.4km/h (5.8mph), providing calm days perfect for coastal fun. Although some reduction in daylight hours occurs, they still linger around 11.8 hours, ensuring extended outdoor activities. Transitioning from November, December carries forward the decreasing rainfall trend. The conclusion of December ushers in a new climatic year, setting the stage for January to take over again with its distinctive weather traits.

Temperature

The start of December sees the average high-temperature at a still moderately hot 28.9°C (84°F), showing little difference from November's 29.2°C (84.6°F). An average low-temperature of 24.8°C (76.6°F), slightly less than the daytime peak, marks the month of December.

Heat index

December's average heat index is computed to be a tropical 34°C (93.2°F). Implement more preventive measures, heat cramps and heat exhaustion are probable. Heatstroke might result from extended activity.
In terms of the heat index, values are set with light wind and shade conditions in mind. Direct exposure to sunshine could lead to a heat index increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. Additional elements encompassing metabolic differences, the degree of physical activity, and attire can impact the individual's perception of temperature. Given the impact of direct sunlight, it's noteworthy that the felt temperature can rise by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to babies and toddlers. Youngsters generally face more threats than adults given their lesser ability to sweat. Coupled with their larger skin surface relative to their small bodies and higher heat production due to their activities, they are more endangered.

Humidity

In December, the average relative humidity is 79%.

Rainfall

In Unawatuna, in December, it is raining for 22.1 days, with typically 114mm (4.49") of accumulated precipitation. Throughout the year, there are 286.9 rainfall days, and 1974mm (77.72") of precipitation is accumulated.

Sea temperature

January, February, June through October and December, with an average sea temperature of 28°C (82.4°F), are months with the coldest seawater.
Note: Engaging in water activities, such as swimming or diving, in temperatures from 25°C (77°F) to 29°C (84.2°F) is very pleasurable for extended periods, without any discomfort.

Daylight

The month with the shortest days is December, with an average of 11h and 48min of daylight.
On the first day of the month, sunrise is at 06:04 and sunset at 17:52. On the last day of December, sunrise is at 06:18 and sunset at 18:05 +0530.

Sunshine

December has the least sunshine of the year, with an average of 7h of sunshine.

UV index

The months with the highest UV index are January through April, June through August, October through December, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health hazard from unprotected exposure to Sun's UV rays for the average person.
Note: In December, the average maximum UV index of 7 translates into the following recommendations:
Endorse precautions and be consistent with sun safety guidelines. Preventing sunburn is paramount. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is particularly strong, noting that parasols or canopies may not offer total sun protection. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly. Notice! The reflection of water and sand increases the UV radiation significantly.