Usually the weather in San Sebastian in the course of September is 18, with highs being around 25 degrees and a low of 14. Our table below has the full details:
| Month | Degrees Celsius |
|---|---|
| Temperature | 18 |
| High Temperature | 25 |
| Low Temperature | 14 |
| Sunshine Per Day | 7 |
Useful Links: San Sebastian Weather: Average Weather & Yearly Climate