Climate averages 1991–2020
Hạ Long weather
in September.
A hot, very wet month: the 4th warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Hạ Long: daytime highs average 29.6°C and nights cool to about 25.0°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 243 mm of rain on roughly 20 days, which makes September a very wet month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 17 min on an average September day.
The nearest other city in this atlas is Cẩm Phả (22 km away). In September its highs average 29.3°C, about as warm as Hạ Long, with 296 mm of rain.
Among the 136 cities listed in Vietnam, Hạ Long ranks joint 97th of 136 for the warmest September highs and joint 47th of 136 for the driest September (rainfall, lowest first). The mean September high of those 136 cities is 29.7°C; Hạ Long is level with that mean.
From September to October, average highs fall by 1.8°C to 27.8°C, and monthly rainfall falls from 243 mm to 104 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Hạ Long climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 19.1°C14.6°C | 14.6°C | 34 | 6.4 | 11.011 h |
| February | 20.5°C15.8°C | 15.8°C | 21 | 5.7 | 11.411 h |
| March | 23.2°C18.5°C | 18.5°C | 43 | 8.8 | 12.012 h |
| April | 26.7°C21.8°C | 21.8°C | 69 | 11.6 | 12.613 h |
| May | 29.3°C24.8°C | 24.8°C | 219 | 19.5 | 13.113 h |
| June | 30.8°C26.8°C | 26.8°C | 266 | 22.4 | 13.413 h |
| July | 30.7°C26.8°C | 26.8°C | 305 | 24.3 | 13.313 h |
| August | 30.4°C26.1°C | 26.1°C | 381 | 26.2 | 12.813 h |
| September, selected | 29.6°C25.0°C | 25.0°C | 243 | 20.0 | 12.312 h |
| October | 27.8°C22.9°C | 22.9°C | 104 | 11.9 | 11.712 h |
| November | 24.8°C19.6°C | 19.6°C | 51 | 8.2 | 11.211 h |
| December | 20.8°C15.8°C | 15.8°C | 31 | 5.9 | 10.911 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Cẩm Phả in SeptemberVietnam · 22 kmHigh 29.3°C · Low 25.0°C · 296 mm rain
- Haiphong in SeptemberVietnam · 42 kmHigh 29.9°C · Low 24.4°C · 290 mm rain
- Kiến An in SeptemberVietnam · 49 kmHigh 29.7°C · Low 24.7°C · 290 mm rain
- Thị Trấn Mạo Khê in SeptemberVietnam · 51 kmHigh 30.2°C · Low 24.1°C · 236 mm rain
- Thị Trấn Đông Triều in SeptemberVietnam · 60 kmHigh 30.2°C · Low 24.1°C · 236 mm rain
- Chũ in SeptemberVietnam · 71 kmHigh 30.0°C · Low 23.4°C · 233 mm rain
- Hải Dương in SeptemberVietnam · 77 kmHigh 30.2°C · Low 24.2°C · 243 mm rain
- Chí Linh in SeptemberVietnam · 80 kmHigh 30.3°C · Low 24.1°C · 243 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Hạ Long) is explained once on the Hạ Long year overview and on the Sources, method and limits page.