December weather forecast
Dehiwala, Sri Lanka

December marks the end of the year in Dehiwala with a continued decrease in rain accompanied by slightly cooler temperatures both during the day and night. The close comparison between November and December's weather places them on a similar spectrum despite slight changes in conditions. December distinguishes itself with the least amount of rainfall in the year at 156mm (6.14"), marking a significant drop from November. As December ends, Dehiwala looks forward to starting the New Year with January's mildly warm temperatures and comparitively lower rain levels.

Temperature

The advent of December in Dehiwala reveals an average high-temperature of a warm 29.7°C (85.5°F), showing minimal difference from the prior month. Dehiwala registers a consistent average low-temperature of 24.1°C (75.4°F) during December.

Heat index

The average heat index in December is estimated at a very hot 36°C (96.8°F). Exercise enhanced safety steps, heat cramps and heat exhaustion are probable. Heatstroke could be a result of sustained activity.
When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'real feel', is a calculation that merges air temperature and relative humidity to depict the sensation of warmth. Elements such as metabolic variations, pregnancy, and physical exertion can shape one's weather perception. Be mindful that being in direct sunlight might mean feeling hotter, with the heat index rising by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly relevant to babies and toddlers. Kids generally face higher risks than adults as they sweat less. Along with their large skin surface compared to their small bodies and higher heat production due to their activities, their vulnerability is increased.
The body's natural response to excessive warmth is perspiration, as it allows for cooling through sweat evaporation. Increased relative humidity slows down evaporation, thereby decreasing the rate of heat removal from the body, culminating in a sensation of overheating. When heat uptake goes beyond the body's cooling mechanisms, there's a surge in body temperature, posing health risks.

Humidity

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

Rainfall

In Dehiwala, during December, the rain falls for 22.4 days and regularly aggregates up to 156mm (6.14") of precipitation. In Dehiwala, during the entire year, the rain falls for 285.6 days and collects up to 2201mm (86.65") of precipitation.

Sea temperature

In Dehiwala, Sri Lanka, the average seawater temperature in December is 28.1°C (82.6°F).
Note: Water temperatures in the range of 25°C (77°F) to 29°C (84.2°F) are warm and delightful, ensuring comfort during water activities over extended periods.

Daylight

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

Sunshine

The average sunshine in December in Dehiwala is 7h.

UV index

January through April, June, July, September, November and December, with an average maximum UV index of 7, are months with the highest UV index in Dehiwala. A UV Index estimate of 6 to 7 represents a high health vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: The UV index of 7 during December leads to these advisories:
Sustain precautions and conform to sun safety norms. Preventing sunburn is necessary. It's important to stay in the shade and limit exposure to the sun from 10 a.m. to 4 p.m., when UV radiation is most intense, although remember that shade structures may not provide full sun protection. Always opt for UVA and UVB-resistant sunglasses on radiant days. Note! Reflective surfaces like sand and water heighten the UV radiation levels.