September weather forecast
Jakarta, Indonesia

September marks a transition period in Jakarta's weather, as the dry season begins to give way to the rainy season. The rainfall sees a steady increase from 35mm in August to 46mm. Despite this, the city's weather remains predominantly dry, with only a slight uptick in the number of rainy days. Variations in the temperatures, sea temperature, wind speeds, and pressure remain within minor ranges, signaling stable weather conditions. Come September, sun enthusiasts still relish the extended sunshine hours, while rainfall begins to gradually saturate the terrain.

Temperature

Jakarta transitions into September recording an average high-temperature of a still tropical 31.2°C, closely aligning with the preceding month's temperature. In Jakarta, an average temperature of 25°C is noted during September nights.

Heat index

The average heat index in September is estimated at a sweltering 38°C. Ensure extra safety measures, heat exhaustion and heat cramps are likely. Continuous activity might result in heatstroke.
Keep in mind the heat index values are meant for areas in shade and with light wind. Heat index values may be hiked up by 15 Fahrenheit (8 Celsius) degrees under direct sunshine.
Note: The heat index, also known as 'apparent temperature' or 'feels like', blends air temperature and moisture content to represent the felt temperature to humans. Factors including metabolic differences, physical activity, and clothing are additional elements that influence the individual's temperature experience. It is essential to be conscious of the fact that direct sunlight can intensify the felt heat, leading to an elevation in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Children often lack awareness of the importance of taking breaks and rehydrating. The feeling of thirst is a late indication of dehydration, so maintaining hydration, especially during long periods of physical activity, is critical.
Perspiring is how the human body naturally cools down, as sweat's evaporation takes away excess heat. In situations of high air temperature combined with high humidity (significant heat index), the body's ability to perspire is reduced, heightening the sense of warmth. Heat absorption that surpasses the body's shedding capability can lead to overheating and varying levels of dehydration.

Humidity

The average relative humidity in September is 68%.

Rainfall

In September, the rain falls for 13.5 days. Throughout September, 46mm of precipitation is accumulated. Throughout the year, there are 252 rainfall days, and 1150mm of precipitation is accumulated.

Sea temperature

In September, the average sea temperature is 29°C.
Note: Swimming, diving, and other water activities in temperatures ranging from 25°C to 29°C are highly enjoyable and provide prolonged comfort without unease.

Daylight

In September, the average length of the day is 12h and 4min.
On the first day of September in Jakarta, sunrise is at 05:53 and sunset at 17:52. On the last day of the month, sunrise is at 05:38 and sunset at 17:47 WIB.

Sunshine

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

UV index

The months with the highest UV index are January through December, with an average maximum UV index of 7. The months with the lowest UV index are January through December, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV radiation for ordinary individuals.
Note: A daily maximum UV index of 7 in September translates into the following instructions:
Eschew overexposure. Those with light skin may suffer burns in fewer than 20 minutes. Avoid direct sunlight between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. Keep in mind that shade structures may not provide complete protection. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Be on guard! The reflective nature of sand and water boosts UV exposure.