September weather forecast and climate
Jakarta, Indonesia

The cityscape of Jakarta, Indonesia, under a dramatic evening skyline
The cityscape of Jakarta, Indonesia, under a dramatic evening skyline
The first month of the spring, September, is also a hot month in Jakarta, Indonesia, with temperature in the range of an average high of 31.2°C (88.2°F) and an average low of 25°C (77°F).

Temperature

In September, the average high-temperature is almost the same as in August - a still hot 31.2°C (88.2°F). In Jakarta, the average low-temperature is 25°C (77°F).

Heat index

The average heat index is calculated to a very hot 37.5°C (99.5°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. With the 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 'feels like', 'real feel', 'felt air temperature', or 'apparent temperature', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. Additional factors like metabolic differences, clothing, wind, and activity influence one's weather impression. 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. 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

The average relative humidity in Jakarta is 68%.

Rainfall

In September, the rain falls for 13.5 days. Throughout September, 46mm (1.81") of precipitation is accumulated. In Jakarta, during the entire year, the rain falls for 252 days and collects up to 1150mm (45.28") of precipitation.

Sea temperature

In Jakarta, the average water temperature is 29°C (84.2°F).
Note: Water temperature between 25°C (77°F) and 29°C (84.2°F) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

Daylight

The average length of the day in Jakarta, Indonesia, is 12.1h.

Sunshine

In September, the average sunshine is 9.6h.

UV index

January through December, with an average maximum UV index of 7, are months with the highest UV index. Months with the lowest UV index in Jakarta are January through December, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health vulnerability from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 7 in September 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. 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. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in September in Jakarta?

In Jakarta, in September, the average high-temperature is 31.2°C (88.2°F), and the average low-temperature is 25°C (77°F). The average heat index (a.k.a. 'feels like', 'felt air temperature'), that combines air temperature and relative humidity, in September is appraised at 37.5°C (99.5°F).

What is the average humidity in September in Jakarta?

The average relative humidity in September in Jakarta, Indonesia, is 68%.

How many days does it rain in September in Jakarta?

In September, the rain falls for 13.5 days. Throughout September, 46mm (1.81") of precipitation is accumulated.

How warm is the water in September in Jakarta?

In September, the average sea temperature is 29°C (84.2°F). For any water activity, surface water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered as excellent and extremely pleasant for lengthened periods.

How many hours of daylight does Jakarta have in September?

In Jakarta, the average length of the day in September is 12.1h.

How long on average sun shines in September in Jakarta?

In Jakarta, Indonesia, the average sunshine in September is 9.6h.

What are the months with the highest UV index in Jakarta?

January through December, with an average maximum UV index of 7, are months with the highest UV index in Jakarta, Indonesia.

What is the month with the lowest UV index in Jakarta?

January through December, with an average maximum UV index of 7, are months with the lowest UV index.

What is the UV index reading in September in Jakarta?

The average daily maximum UV index in September in Jakarta, Indonesia, is 7. A UV Index reading of 6 to 7 represents a high hazard to health from the exposure to the Sun's UV rays.
Average temperature in September - Jakarta, Indonesia
  • Average high temperature in September: 31.2°C

The warmest month (with the highest average high temperature) is October (31.8°C).
Months with the lowest average high temperature are January and February (29.8°C).

  • Average low temperature in September: 25°C

The month with the highest average low temperature is November (26.5°C).
The coldest month (with the lowest average low temperature) is August (24.7°C).

Average pressure in September - Jakarta, Indonesia
  • Average pressure in September: 1011.1mbar

The month with the highest atmospheric pressure is September (1011.1mbar).
The month with the lowest atmospheric pressure is December (1009.2mbar).

Average wind speed in September - Jakarta, Indonesia
  • Average wind speed in September: 8.8km/h

The windiest month (with the highest average wind speed) is January (12.4km/h).
The calmest month (with the lowest average wind speed) is November (8.1km/h).

Average humidity in September - Jakarta, Indonesia
  • Average humidity in September: 68%

The month with the highest relative humidity is February (76%).
The month with the lowest relative humidity is October (67%).

Average rainfall in September - Jakarta, Indonesia
  • Average rainfall in September: 46mm

The wettest month (with the highest rainfall) is March (144mm).
The driest month (with the least rainfall) is August (35mm).

Average rainfall days in September - Jakarta, Indonesia
  • Average rainfall days in September: 13.5 days

The month with the highest number of rainy days is March (26.1 days).
The month with the least rainy days is August (11.6 days).

Average sea temperature in September - Jakarta, Indonesia
  • Average sea temperature in September: 29°C

The best months for swimming (with the highest average sea temperature) are April and May (30°C).
The coldest months (with the lowest average sea temperature) are January and February (28°C).

Average daylight in September / Average sunshine in September - Jakarta, Indonesia
  • Average daylight in September: 12.1h

The month with the longest days is December (Average daylight: 12.5h).
Months with the shortest days are May, June and July (Average daylight: 11.8h).

  • Average sunshine in September: 9.6h

The month with the most sunshine is March (Average sunshine: 10.2h).
The month with the least sunshine is July (Average sunshine: 7.3h).

Average sunshine days in September - Jakarta, Indonesia
  • Average sunshine days in September: 14.5 days

The month with the most sunshine days is August (16 days).
The month with the least sunshine days is February (2.6 days).

Average UV index in September - Jakarta, Indonesia
  • Average UV index in September: 7

Months with the highest UV index are January, February, March, April, May, June, July, August, September, October, November and December (UV index 7).
Months with the lowest UV index are January, February, March, April, May, June, July, August, September, October, November and December (UV index 7).

Average cloud cover in September - Jakarta, Indonesia
  • Average cloud cover in September: 22

The month with the most cloud cover is January (Cloud cover 46).
The month with the least cloud cover is August (Cloud cover 21).

Average visibility in September - Jakarta, Indonesia
  • Average visibility in September: 10km

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).