Hanoi weather in September
In September, Hanoi has daytime highs averaging 30 °C, nights around 24 °C, with 19 wet days. Figures are 1991–2020 climate normals.
- 30.3°C Average high
- 24.1°C Average low
- 19days Wet days
- 242mm Rainfall
- 12h Daylight
Daily temperatures through September
How September develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 September | 30.8 °C | 24.8 °C | 74 % |
| 11–20 September | 30.3 °C | 24.1 °C | 64 % |
| 21–30 September | 29.8 °C | 23.3 °C | 50 % |
- Rain is most likely over days 1–10 of September (74 % of days) and least likely over days 21–30 (50 %).
What to expect
| Measure | Typical September | Share of the month |
|---|---|---|
| Days above 25 °C | 29 of 30 | 98 % |
| Days above 30 °C | 19 of 30 | 63 % |
| Days below 0 °C | 0 of 30 | 0 % |
| Days with more than 1 mm rain | 19 of 30 | 62 % |
Conditions in September
| Measure | Average |
|---|---|
| Mean temperature | 27 °C |
| Record high (1991–2020) | 35 °C |
| Record low (1991–2020) | 18 °C |
| Relative humidity | 84 % |
| Wind speed | 11 km/h |
| Cloud cover | 71 % |
September compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| July | 32.3 °C | 267 mm | 85 % |
| August | 31.4 °C | 320 mm | 82 % |
| September | 30.3 °C | 242 mm | 71 % |
| October | 28.2 °C | 121 mm | 58 % |
| November | 25.0 °C | 57 mm | 58 % |
See all twelve months for Hanoi
- September is the 5th warmest month here.
- It is the 10th driest month of the year.
- It ranks 4th for least cloud cover.
- Days last about 12 hours from sunrise to sunset.
- It rains on 19 of 30 days — 62 % of the month.
- Nights are about 6.2 °C cooler than the middle of the day.
- The hottest September day on record since 1991 reached 35 °C, 4.9 °C above the usual daytime high.
QuestionsSeptember in Hanoi, answered
How warm is Hanoi in September?
Daily highs average 30 °C and nights fall to about 24 °C, a spread of 6.2 °C between afternoon and dawn. That makes September the 5th warmest month of the year here.
Does it rain much in Hanoi in September?
September averages 242 mm of rain, spread over about 19 of the 30 days — 62 % of the month. Cloud cover averages 71 % of the sky.
How long are the days in September?
Hanoi averages 12 hours between sunrise and sunset in September. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.