San Sebastián weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Good
Best time to visit: May – October
What is the weather like in San Sebastián in September?
In September, San Sebastián is warm: daytime highs average 22 °C, and nights cool down to about 16 °C. The sea averages 21.1 °C – refreshing for a swim. Expect around 6 hours of sunshine a day. Rain is frequent, with about 13 rainy days and 92 mm in total. All in all, September is a good month for a holiday in San Sebastián.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 73 | 72 | 65 |
| Day | 23° | 22° | 19° |
| Night | 17° | 16° | 14° |
| Sea | 22° | 21° | 19° |
| Sun | 7 h | 6 h | 5 h |
| Rain days | 13 | 13 | 14 |
More details for September
- Daylight
- 12 h 34 min07:46 – 20:20
- UV index
- 6 · highclear sky, noon (estimate)All months
- Muggy days
- 2 daysdew point 18 °C or more
- Wind
- 16 km/haverage daily peak
- Cloud cover
- 58 %on average
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+2Europe/Madrid
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %53 %
- Few rainy daysweight 30 %37 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Swimwear
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
San Sebastián in September: quick answers
Is San Sebastián hot in September?
Warm rather than hot: in September, daytime highs in San Sebastián average 22 °C and nights cool to about 16 °C.
Can you swim in San Sebastián in September?
Yes. In September the sea averages 21.1 °C – refreshing for a swim.
Does it rain much in San Sebastián in September?
Rain is frequent, with about 13 rainy days and 92 mm in total.
San Sebastián month by month
The whole year in San SebastiánAll destinations: SpainWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0)