The best time to go to San Sebastian is during the summer months, from December to February, when the weather is warm and sunny, superb for enjoying the beach and outdoor activities.During this period, the average daily temperature hovers around 25°C, with highs often reaching 30°C. The ocean is also at its warmest, making it ideal for swimming and water sports. This is peak season, so the town is at its most lively, with many restaurants, shops, and attractions fully open.If you prefer slightly milder weather and fewer crowds, the shoulder seasons of spring (September to November) and autumn (March to May) are also excellent choices. Temperatures are pleasant, typically ranging from 18°C to 23°C, and there's still plenty of sunshine.