San Sebastián weather in September
September in San Sebastián: hot, dry, with clean air — a great time to visit.
#10 of 12 months in San Sebastián · #329 of 604 destinations to visit in September · comfort 79/100 (tier B)
Updated June 2026 · climate normals from ERA5 reanalysis
San Sebastián climate normals — September
| Daytime high | 26°C / 80°F | 🥵 hot |
|---|---|---|
| Nighttime low | 24°C / 76°F | |
| Feels like (high) | 31°C / 88°F | |
| Rainfall | 16 mm / 0.6 in | ☀️ dry |
| Rainy days | 1 days | |
| Humidity | 77% | 💦 very humid |
| Dew point | 21°C / 69°F | |
| Sunshine | 11 h/day | |
| Daylight | 12.3 h | |
| Wind | 19 km/h / 12 mph | |
| Air quality (US AQI) | 36 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Where is San Sebastián?
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San Sebastián in September — FAQ
- Is September a good time to visit San Sebastián?
- September in San Sebastián: hot, dry, with clean air — a great time to visit. It ranks #10 of 12 months for San Sebastián on SeasonMap's comfort score (79/100).
- What is the weather like in San Sebastián in September?
- In September, San Sebastián averages a daily high of 26.4°C and a low of 24.2°C, with about 16 mm of rain over roughly 0.8 rainy days.
- What is the air quality in San Sebastián in September?
- San Sebastián has a mean US Air Quality Index of about 36 in September.