Cat Ba Island weather by month
Cat Ba Island runs from about 18°C in January to 29°C in August, with September the wettest month at 743 mm.
warmest month
August
29°C
coolest month
January
18°C
wettest month
September
743 mm
worst air month
February
30 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 18°C | 59 mm | 138 h | 26 |
| February | 19°C | 25 mm | 113 h | 30 |
| March | 20°C | 44 mm | 117 h | 24 |
| April | 26°C | 51 mm | 255 h | 25 |
| May | 27°C | 209 mm | 285 h | 16 |
| June | 29°C | 273 mm | 255 h | 16 |
| July | 29°C | 443 mm | 272 h | 27 |
| August | 29°C | 223 mm | 300 h | 18 |
| September | 28°C | 743 mm | 216 h | 14 |
| October | 26°C | 69 mm | 289 h | 16 |
| November | 24°C | 24 mm | 288 h | 18 |
| December | 19°C | 15 mm | 223 h | 28 |
About 2,751 hours of sun a year. Roughly 159 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 2026-05-25. Full method, licences and the list of sources we rejected are on the methodology page.