December weather forecast
Dumai, Indonesia

The first month of the winter, December, is still a hot month in Dumai, Indonesia, with an average temperature varying between 30.6°C (87.1°F) and 23.7°C (74.7°F).

Temperature

In Dumai, the coldest period comes during January and December, when the average high-temperature touches 30.6°C (87.1°F).

Heat index

For most parts of December, the heat index is calculated to be an extremely hot 41°C (105.8°F). Ensure additional precautions, heat exhaustion and heat cramps may be expected. Heatstroke could occur from sustained activity.
Research indicates the heat index considers values in shaded locales and with light winds. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. Factors such as metabolic variation, pregnancy, and physical activity play a role in one's impression of weather. Direct sun rays can make one feel hotter, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Children often overlook the need for breaks and fluid intake. Thirst is a late-stage sign of dehydration - hence, it is necessary to stay hydrated, especially during extended periods of physical activities.
The natural method the human body uses to remove excess heat is by perspiring and letting sweat evaporate. With a high level of moisture in the air, the evaporation process becomes less efficient, preventing the body from cooling down efficiently and resulting in a sensation of overheating. Heat-related disorders may develop if heat gain in the body overshadows its cooling capacity, leading to elevated temperatures.

Humidity

The months with the highest humidity are November and December, with an average relative humidity of 83%.

Rainfall

In Dumai, Indonesia, in December, during 24.1 rainfall days, 120mm (4.72") of precipitation is typically accumulated. Throughout the year, there are 286.4 rainfall days, and 1200mm (47.24") of precipitation is accumulated.

Sea temperature

In December, the average sea temperature is 29.3°C (84.7°F).
Note: For activities in the water such as swimming or diving, temperatures from 25°C (77°F) to 29°C (84.2°F) are considered optimal for prolonged enjoyment without discomfort.

Daylight

The month with the shortest days is December, with an average of 12h and 0min of daylight.
On the first day of the month, sunrise is at 06:02 and sunset at 18:04. On the last day of December, sunrise is at 06:16 and sunset at 18:18 WIB.

Sunshine

The month with the least sunshine is December, with an average of 7h of sunshine.

UV index

The months with the lowest UV index are October and December, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum daily UV index of 6 in December interprets into the following recommendations:
Act on precautions and pay attention to sun safety recommendations. Avoidance of sunburn is obligatory. Avoid direct Sun exposure and stay in the shade between 10 a.m. and 4 p.m., a time when UV radiation is most intense, noting that not all shade structures offer full protection. Stay sun-safe with clothing that is both closely woven and worn loosely. Beware! Reflections from sand and water can intensify the Sun's UV radiation.