September weather forecast
Jember, Indonesia

September ushers in a transition phase from the hot, dry August to the cooler, wetter months that follow in Jember. The rainfall begins to increase, averaging at 18mm (0.71"), providing signals towards an upcoming wet season. Similarly, the heightened temperatures from August begin to slightly drop, offering somewhat cooler days. However, the humidity remains relatively low, maintaining general comfort levels in the city. Towards the end of September, the days start to gradually become shorter, paving the way for the ensuing season.

Temperature

As Jember steps into September, the average high-temperature holds at a still tropical 33.4°C (92.1°F), hinting at a minor fluctuation from the prior month. Jember records a consistent low-temperature of 22.1°C (71.8°F) during September nights.

Heat index

The heat index value for September is estimated at a blistering 43°C (109.4°F). Observe: Heat exhaustion and heat cramps are probable. Heatstroke is on the horizon with prolonged exertion.
It is worth noting that heat index values are gauged for conditions in the shade and light breezes. The heat index may scale up by 15 Fahrenheit (8 Celsius) degrees with direct sun exposure.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. The impression of weather on a person can be swayed by additional aspects, including metabolic variations, pregnancy, and activity levels. Always consider that direct sunlight exposure might heighten the heat's effects, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Children usually face more risks than adults as their ability to sweat is less. Additionally, their larger skin surface in relation to their petite bodies and higher heat output due to their activities increases their vulnerability.
In high temperatures, perspiration kicks in, allowing the human body to cool down through the evaporation of sweat. When relative humidity is on the rise, it curtails evaporation, thereby reducing the heat elimination from the body and causing the feeling of being excessively hot. When the body's heat gain surpasses its removal capacity, body temperature starts to climb, leading to potential heat-related ailments.

Humidity

The months with the lowest humidity are September and October, with an average relative humidity of 65%.

Rainfall

In September, in Jember, the rain falls for 7.8 days. Throughout September, 18mm (0.71") of precipitation is accumulated. In Jember, Indonesia, during the entire year, the rain falls for 247.8 days and collects up to 1536mm (60.47") of precipitation.

Daylight

In Jember, the average length of the day in September is 12h and 4min.
On the first day of the month, sunrise is at 05:26 and sunset at 17:23. On the last day of September, sunrise is at 05:09 and sunset at 17:20 WIB.

Sunshine

In September, the average sunshine is 9.6h.

UV index

February, April through December, with an average maximum UV index of 7, are months with the highest UV index in Jember. A UV Index of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV rays for ordinary individuals.
Note: In September, an average UV index of 7 transforms into the following instructions:
Employ safeguards and advocate sun safety protocols. Shielding against skin and eye damage is crucial. The Sun's UV radiation is most potent between 10 a.m. and 4 p.m. Try to limit direct exposure to the Sun during this period. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.