August repeats July with more people on it. Spain takes its holidays this month and the northern coast is where the rest of the country goes to escape forty degrees inland, so Zarautz's two and a half kilometres of sand fill up and San Sebastián books out.
The middle of the month is worth knowing about before choosing dates. Semana Grande fills San Sebastián for a week in mid-August, with fireworks fired from the bay every night and the old town shoulder to shoulder until morning. Whether that is the reason to come or the reason to come a fortnight later is a real question, and it decides more about the week than the forecast does.
The water is at 23°C, the warmest it gets, and the wetsuit spends the week in the car.
