Castro weather by month
Castro runs from about 6°C in July to 15°C in January, with June the wettest month at 333 mm.
warmest month
January
15°C
coolest month
July
6°C
wettest month
June
333 mm
worst air month
December
5 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 15°C | 36 mm | 367 h | 4 |
| February | 15°C | 41 mm | 317 h | 4 |
| March | 12°C | 142 mm | 275 h | 4 |
| April | 10°C | 115 mm | 207 h | 4 |
| May | 7°C | 115 mm | 198 h | 3 |
| June | 8°C | 333 mm | 109 h | 4 |
| July | 6°C | 84 mm | 175 h | 3 |
| August | 7°C | 147 mm | 190 h | 4 |
| September | 8°C | 273 mm | 179 h | 4 |
| October | 10°C | 31 mm | 298 h | 4 |
| November | 11°C | 184 mm | 268 h | 4 |
| December | 13°C | 56 mm | 374 h | 5 |
About 2,957 hours of sun a year. Roughly 153 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.