Weather will likely play an important role when you plan your trip to San Sebastian, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually March and April, with an average temperature of 26°C, while the coldest months are December and January, with an average of 25°C. The rainiest months in San Sebastian are September, June, May and August, with each month seeing an average of 463 mm of rainfall.