Interlaken weather by month
Interlaken runs from about 4°C in December to 22°C in August, with April the wettest month at 221 mm.
warmest month
August
22°C
coolest month
December
4°C
wettest month
April
221 mm
worst air month
March
8 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 5°C | 155 mm | 168 h | 4 |
| February | 8°C | 88 mm | 188 h | 3 |
| March | 8°C | 179 mm | 219 h | 8 |
| April | 10°C | 221 mm | 246 h | 6 |
| May | 13°C | 201 mm | 274 h | 4 |
| June | 18°C | 195 mm | 299 h | 5 |
| July | 21°C | 156 mm | 358 h | 3 |
| August | 22°C | 57 mm | 347 h | 6 |
| September | 15°C | 210 mm | 243 h | 3 |
| October | 14°C | 145 mm | 218 h | 5 |
| November | 8°C | 111 mm | 214 h | 3 |
| December | 4°C | 157 mm | 160 h | 4 |
About 2,934 hours of sun a year. Roughly 190 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.