Ha Long Bay weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Poor
Best time to visit: November – April
What is the weather like in Ha Long Bay in September?
In September, Ha Long Bay is hot: daytime highs average 30 °C, and even at night it stays warm at around 25 °C. The sea averages 29.4 °C – almost as warm as a bath. Expect around 5 hours of sunshine a day. It rains often – on about 21 days, adding up to 265 mm. On about 15 days the thermometer climbs to 30 °C or more. The air is often humid and muggy. All in all, September is not an ideal month for a holiday in Ha Long Bay.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 29 | 36 | 61 |
| Day | 31° | 30° | 28° |
| Night | 26° | 25° | 23° |
| Sea | 30° | 29° | 28° |
| Sun | 5 h | 5 h | 5 h |
| Rain days | 27 | 21 | 13 |
More details for September
- Daylight
- 12 h 17 min05:38 – 17:56
- UV index
- 11 · extremeclear sky, noon (estimate)All months
- Muggy days
- 29 daysdew point 18 °C or moreAll months
- Wind
- 14 km/haverage daily peakAll months
- Cloud cover
- 71 %on averageAll months
- Hot days
- 15 days30 °C or moreAll months
- Time zone
- UTC+7Asia/Bangkok
How the score comes together
- Temperatureweight 50 %59 %
- Sunshineweight 20 %32 %
- Few rainy daysweight 30 %0 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Nature escape”.
What to pack in September
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Water bottle – drink plenty
- Insect repellent
- Rain jacket or umbrella
Ha Long Bay in September: quick answers
Is Ha Long Bay hot in September?
Yes. In September, Ha Long Bay is hot: daytime highs average 30 °C and nights stay around 25 °C. On about 15 days the thermometer climbs to 30 °C or more.
Can you swim in Ha Long Bay in September?
Yes. In September the sea averages 29.4 °C – almost as warm as a bath.
Does it rain much in Ha Long Bay in September?
It rains often – on about 21 days, adding up to 265 mm.
Ha Long Bay month by month
The whole year in Ha Long BayAll destinations: VietnamWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences