Hanoi weather by month
Hanoi runs from about 18°C in January to 29°C in June, with September the wettest month at 629 mm.
warmest month
June
29°C
coolest month
January
18°C
wettest month
September
629 mm
worst air month
April
67 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 18°C | 111 mm | 91 h | 54 |
| February | 19°C | 28 mm | 110 h | 46 |
| March | 22°C | 77 mm | 112 h | 43 |
| April | 28°C | 29 mm | 214 h | 67 |
| May | 27°C | 308 mm | 219 h | 40 |
| June | 29°C | 538 mm | 221 h | 43 |
| July | 29°C | 541 mm | 263 h | 53 |
| August | 29°C | 319 mm | 269 h | 49 |
| September | 27°C | 629 mm | 201 h | 49 |
| October | 25°C | 58 mm | 282 h | 41 |
| November | 24°C | 10 mm | 245 h | 43 |
| December | 18°C | 12 mm | 154 h | 62 |
About 2,381 hours of sun a year. Roughly 183 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-22. Full method, licences and the list of sources we rejected are on the methodology page.