Hanoi
Vietnam
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Hanoi, Vietnam

The beautiful Tran Quoc Pagoda in Hanoi, Vietnam, with a view of more city structures in the far background
The beautiful Tran Quoc Pagoda in Hanoi, Vietnam, with a view of more city structures in the far background
The first month of the autumn, September, is still a tropical month in Hanoi, Vietnam, with average temperature fluctuating between 24.2°C (75.6°F) and 31.7°C (89.1°F).

Temperature

In September, the average high-temperature is essentially the same as in August - a still tropical 31.7°C (89.1°F). In September, in Hanoi, the average low-temperature is 24.2°C (75.6°F).

Heat index

In September, the average heat index is appraised at a blistering 43.3°C (109.9°F). Beware - heat cramps and heat exhaustion are very likely. Heatstroke is imminent with prolonged activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'feels like', 'real feel', or 'apparent temperature', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. Additional factors like pregnancy, clothing, differences in body mass, height, and shape, and activity influence one's weather impression. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

August and September, with an average relative humidity of 80%, are most humid months in Hanoi.

Rainfall

In Hanoi, in September, during 18.5 rainfall days, 73mm (2.87") of precipitation is typically accumulated. Throughout the year, in Hanoi, there are 181.2 rainfall days, and 595mm (23.43") of precipitation is accumulated.

Daylight

The average length of the day in September is 12.3h.

Sunshine

In Hanoi, Vietnam, the average sunshine is 8.5h.

UV index

Months with the highest UV index in Hanoi, Vietnam, are May through September, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high health hazard from the exposure to the Sun's UV rays for the ordinary person.
Note: In September, the average maximum UV index of 7 translate into the following recommendations:
Take precautions against overexposure. Protection against sun damage is needed. 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. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.

What is the temperature in September in Hanoi?

In September, in Hanoi, Vietnam, the average high-temperature is 31.7°C (89.1°F), and the average low-temperature is 24.2°C (75.6°F). The average heat index (a.k.a. 'felt air temperature', 'feels like'), that combines air temperature and relative humidity, in September is calculated to 43.3°C (109.9°F).

What are the most humid months in Hanoi?

Months with the highest humidity in Hanoi, Vietnam, are August and September, with an average relative humidity of 80%.

What is the average humidity in September in Hanoi?

The average relative humidity in September in Hanoi is 80%.

How much does it rain in Hanoi in September?

In September, in Hanoi, Vietnam, the rain falls for 18.5 days. Throughout September, 73mm (2.87") of precipitation is accumulated.

What is the average length of the day in September in Hanoi?

In Hanoi, the average length of the day in September is 12.3h.

How many hours of sunshine does Hanoi have in September?

The average sunshine in September is 8.5h.

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

Months with the highest UV index in Hanoi, Vietnam, are May through September, with an average maximum UV index of 7.

How high is the UV index in September in Hanoi?

The average daily maximum UV index in September in Hanoi is 7. A UV Index value of 6 to 7 symbolizes a high health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Hanoi, Vietnam
  • Average high temperature in September: 31.7°C

The warmest month (with the highest average high temperature) is June (35.4°C).
The month with the lowest average high temperature is January (20.7°C).

  • Average low temperature in September: 24.2°C

The month with the highest average low temperature is June (26.6°C).
The coldest month (with the lowest average low temperature) is January (14.4°C).

Average humidity in September - Hanoi, Vietnam
  • Average humidity in September: 80%

Months with the highest relative humidity are August and September (80%).
The month with the lowest relative humidity is December (69%).

Average rainfall in September - Hanoi, Vietnam
  • Average rainfall in September: 73mm

The wettest month (with the highest rainfall) is August (135mm).
The driest month (with the lowest rainfall) is February (7mm).

Average rainfall days in September - Hanoi, Vietnam
  • Average rainfall days in September: 18.5 days

The month with the highest number of rainy days is July (23.3 days).
The month with the lowest number of rainy days is February (7.8 days).

Average daylight in September / Average sunshine in September - Hanoi, Vietnam
  • Average daylight in September: 12.3h

The month with the longest days is June (Average daylight: 13.4h).
The month with shortest days is December (Average daylight: 10.9h).

  • Average sunshine in September: 8.5h

The month with most sunshine is June (Average sunshine: 10.1h).
The month with least sunshine is January (Average sunshine: 3.7h).

Average UV index in September - Hanoi, Vietnam
  • Average UV index in September: 7

Months with the highest UV index are May, June, July, August and September (UV index 7).
The month with the lowest UV index is December (UV index 4).