Nelson weather by month
Nelson runs from about 9°C in July to 19°C in January, with October the wettest month at 249 mm.
warmest month
January
19°C
coolest month
July
9°C
wettest month
October
249 mm
worst air month
November
5 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 19°C | 71 mm | 383 h | 4 |
| February | 18°C | 55 mm | 362 h | 4 |
| March | 15°C | 40 mm | 317 h | 3 |
| April | 14°C | 141 mm | 258 h | 3 |
| May | 10°C | 30 mm | 251 h | 4 |
| June | 10°C | 170 mm | 200 h | 3 |
| July | 9°C | 87 mm | 215 h | 3 |
| August | 10°C | 145 mm | 254 h | 4 |
| September | 11°C | 63 mm | 285 h | 3 |
| October | 13°C | 249 mm | 305 h | 4 |
| November | 15°C | 86 mm | 325 h | 5 |
| December | 18°C | 60 mm | 366 h | 4 |
About 3,521 hours of sun a year. Roughly 121 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 2026-05-27. Full method, licences and the list of sources we rejected are on the methodology page.