San José weather by month
San José runs from about 19°C in November to 22°C in March, with November the wettest month at 676 mm.
warmest month
March
22°C
coolest month
November
19°C
wettest month
November
676 mm
worst air month
August
11 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 21°C | 11 mm | 339 h | 6 |
| February | 21°C | 32 mm | 315 h | 5 |
| March | 22°C | 22 mm | 359 h | 8 |
| April | 22°C | 154 mm | 303 h | 9 |
| May | 21°C | 300 mm | 306 h | 9 |
| June | 20°C | 548 mm | 216 h | 9 |
| July | 20°C | 424 mm | 237 h | 8 |
| August | 20°C | 391 mm | 279 h | 11 |
| September | 20°C | 454 mm | 227 h | 10 |
| October | 20°C | 479 mm | 249 h | 10 |
| November | 19°C | 676 mm | 168 h | 6 |
| December | 20°C | 234 mm | 254 h | 7 |
About 3,252 hours of sun a year. Roughly 254 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.