The best time to visit Santorini is May–June or September–October — when the weather is warm and sunny, the Aegean Sea is swimmable, and the island is far more manageable than during the peak summer crush. The shoulder seasons offer a genuinely superior combination of conditions, value, and atmosphere.
Spring (April–June)
May and June are among the finest months to visit Santorini. Temperatures are warm and comfortable (20–27°C), the sea has warmed to swimmable temperatures (around 20–22°C by June), wildflowers still dot the hillsides, and the island's restaurants and hotels are open and welcoming without the overwhelming July–August crowds. Late April is pleasant but the sea is still cool. This is the peak wedding and honeymoon season — book well in advance, as popular cave hotels fill up early.
Summer (July–August)
High summer on Santorini is intensely busy and expensive. Cruise ships disgorge thousands of day visitors into Fira and Oia daily, queues for the sunset viewpoint in Oia can stretch for hundreds of metres, and temperatures frequently exceed 30°C. The famous meltemi wind, which blows strongly from the north across the Aegean in July and August, can make boat trips uncomfortable and whip up sand on the beaches. Accommodation prices are at their peak, and availability at quality properties is extremely limited. That said, the sea is beautifully warm, the nightlife is lively, and the island's beauty is undimmed — just prepare for crowds and heat.
Autumn (September–October)
September is arguably Santorini's best month. The summer crowds have thinned significantly, but the sea is at its warmest (25–27°C), temperatures are hot but not oppressive (25–30°C), and sunsets are spectacular. Restaurants and hotels are still fully open, and prices start to ease from August peaks. October remains warm (around 22°C) with excellent swimming conditions into mid-month; by late October the first autumnal weather arrives. This is a superb time for couples and foodies, with the harvest season for Santorini's distinctive Assyrtiko wine grapes underway in September.
Winter (November–March)
Santorini in winter is a very different island — quiet, local, and stripped of its tourist apparatus. Most restaurants, bars, and hotels in Oia close entirely from November to March, and the island's famous sunsets take on a melancholy, atmospheric beauty. For the small number of visitors who come in winter, the rewards include deserted caldera pathways, dramatically low prices, and a genuine sense of the island as it was before mass tourism. However, the sea is too cold for swimming, some facilities are closed, and the weather — while mild by northern European standards (10–15°C) — can bring rain and wind.