Cantabria has a genuinely Atlantic climate: mild, green, and often wet. Summer temperatures rarely exceed 25°C, and the rain comes in at any time of year, though July and August tend to be the driest months. The green landscape and fresh air are a contrast to the dry heat of central Spain.
The best time to visit Santillana del Mar is May to June or September to October — warm enough for exploring, before or after the main summer tourist season. August sees the town at its most crowded and prices are at their highest. Winter is quiet and cool, with some accommodation closing; the Altamira Museum stays open year-round but hours are reduced.
The Fiesta de la Vaca is held in late June, a local festival with folklore and traditional Cantabrian events.