September weather forecast
Bangkok, Thailand

With the arrival of September, Bangkok, Thailand reaches the final stretch of the monsoon season. This period sees the highest level of relative humidity at 79%, making it the most humid month of the year. Despite continued rainfall, a gradual fall in sea temperatures and an overall decrease in sunlight hours characterizes the transition period. Slightly cooling temperatures provide relief from the intense heat experienced earlier in the year. The beckoning of the dry season's arrival is felt as the city moves into October.

Temperature

The transition from August to September in Bangkok sees an average high-temperature of a still tropical 32.8°C (91°F), indicating a minor variance from the prior month. During the month of September, the temperature in Bangkok, Thailand, generally drops to a low average of 25°C (77°F).

Heat index

For most parts of September, the heat index is calculated to be a burning hot 47°C (116.6°F). Stay mindful: Heat exhaustion and heat cramps are likely. Heatstroke could follow extended physical effort.
Understanding the heat index involves considering values for shaded locales with light wind. Heat index values have the potential to be boosted by 15 Fahrenheit (8 Celsius) degrees due to direct sunlight.
Note: The heat index, also known as 'apparent temperature' or 'real feel', binds temperature metrics with humidity values to give a sense of the actual warmth. One's perception of weather can be shaped by other factors, involving metabolic differences, pregnancy, and physical exertion. Direct sun exposure is noteworthy in its ability to escalate the felt temperature, potentially adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values hold particular importance for children. Young individuals usually face more risks than adults due to their lower sweat production. Their large skin surface area relative to their tiny bodies and high heat production from their activities adds to their risk.
For the human body, perspiration is the go-to method to regulate temperature, using sweat's evaporation to dissipate warmth. An increase in relative humidity retards evaporation, subsequently reducing the body's heat removal rate and leading to a sensation of being overly warm. With body temperatures on the rise, inefficient heat shedding can lead to dehydration and its associated complications.

Humidity

The most humid month in Bangkok, Thailand, is September, with an average relative humidity of 79%.

Rainfall

The month with the most rainfall is September, when the rain falls for 21 days and typically aggregates up to 334mm (13.15") of precipitation.

Sea temperature

In Bangkok, the average seawater temperature in September is 28.8°C (83.8°F).
Note: Water temperatures between 25°C (77°F) and 29°C (84.2°F) are regarded as very warm, ensuring all water activities are pleasurable for extended periods without feeling uneasy.

Daylight

The average length of the day in September is 12h and 13min.
On the first day of the month, sunrise is at 06:06 and sunset at 18:29. On the last day of September, in Bangkok, sunrise is at 06:07 and sunset at 18:08 +07.

Sunshine

The months with the least sunshine are August and September, with an average of 5.2h of sunshine.

UV index

The months with the highest UV index in Bangkok are February through September, with an average maximum UV index of 12. A UV Index reading of 11, and higher, represents an excessive health risk from exposure to the Sun's UV rays for the average person.
Note: In September, the maximum UV index of 12 transforms into these recommendations:
Enforce every vital precaution. Those with light skin could endure burns in a matter of minutes. Seek shade and limit direct sun exposure between 10 a.m. and 4 p.m., the peak period for UV radiation. Keep in mind that shade structures like parasols or canopies do not offer complete sun protection. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Even when it's cloudy, ensure the generous application and frequent reapplication of a sunscreen with at least 30 SPF, particularly post swim or outdoor activity. Notice! The reflection of water and sand increases the UV radiation significantly.