January weather forecast
Jakarta, Indonesia

January, like December, in Jakarta, Indonesia, is another warm summer month, with an average temperature ranging between max 29.8°C (85.6°F) and min 25.6°C (78.1°F).

Temperature

The coldest months are January and February, with an average high-temperature of 29.8°C (85.6°F).

Heat index

In January, the average heat index is appraised at a sweltering 35°C (95°F). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Note that heat index values are valued for light wind and location in the shade. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'feels like', 'felt air temperature', or 'apparent temperature', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. This effect is individual, with diverse people perceiving weather differently for numerous reasons (pregnancy, differences in body mass, height, and shape, clothing), and activity. 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 particularly important for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
The human body normally cools itself by perspiration, as evaporated sweat carries heat away from the body. A higher relative humidity affects normal body cooling by reducing the evaporation rate, subsequently lowering the rate at which the body cools and increasing the perception of heat. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

In January, the average relative humidity is 73%.

Rainfall

In Jakarta, during January, the rain falls for 24.8 days and regularly aggregates up to 127mm (5") of precipitation. In Jakarta, during the entire year, the rain falls for 252 days and collects up to 1150mm (45.28") of precipitation.

Sea temperature

January and February, with an average sea temperature of 28°C (82.4°F), are months with the coldest seawater in Jakarta.
Note: For swimming, diving, and other water activities, temperatures between 25°C (77°F) and 29°C (84.2°F) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

Daylight

In Jakarta, the average length of the day in January is 12h and 26min.
On the first day of the month, sunrise is at 05:41 and sunset at 18:10. On the last day of January, sunrise is at 05:54 and sunset at 18:17 WIB.

Sunshine

In Jakarta, Indonesia, the average sunshine in January is 9.4h.

UV index

January through December, with an average maximum UV index of 7, are months with the highest UV index in Jakarta. The months with the lowest UV index in Jakarta are January through December, with an average maximum UV index of 7. A UV Index value of 6 to 7 symbolizes a high health vulnerability from unsafe exposure to UV radiation for the average person.
Note: The average daily UV index of 7 in January transform into the following instructions:
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. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.