Temperatures are starting to regularly exceed 70°F this month, as warm sunny weather predominates. There is hardly any rain, either. You'll enjoy ten daily hours of sunlight a day, and seawater temperatures have also increased to 64°F/18°C.
Starting from May and continuing through Santorini's warm weather season, the island can be affected by the Meltemi, a wind from the north that blows persistently for up to several days at a time and is liable to make the air feel cooler: good because it injects some freshness into an otherwise sweltering summer but bad because it can make the sea rough.
For more on weather this month, see Greece in May: Travel Tips, Weather, & More.
Crowds & Costs
May is still shoulder season, and the crowds do not come in the numbers they will for the following three months, but nevertheless the island is getting pretty busy. It may be harder now to book your first-choice hotel room, grab a place on a round-island tour or get a stretch of beach to yourself at any time of the day.
Cost-wise, as this is not yet high season, some prices such as for hotels are not yet at their annual highs (although this will be the case from next month through to the end of August.
Where to Go
This month, as with the following four or five, your first ports of call on Santorini should be the beaches. The selection of beaches on the island is phenomenal, with the majority on the east side of the island, away from the west coast which forms the caldera.
Kamari is a black sand beach with a hotel sitting directly on the sand; other sandy beaches with hotels close by include Perissa and Perivolos beaches. A visit to the striking and aptly named Red Beach, comprised of small red stones and with beautiful crystalline water, is also a great idea, as is the long and lovely Baxedes Beach near Oia.
Either hiking, driving or taking a cruise via the prehistoric city at Akrotiri, hidden away at the southern tip of Santorini, is also a must. These ruins constituted some of the Bronze Age’s most advanced settlements prior to being destroyed by a volcanic eruption in the mid-second millennium CE. In fact, taking a cruise around the island gives you a good feel for which places you would like to return to spend more time at.
Many sights are best taken in on a walk, so you can see them at your leisure. For example, on the hike between Fira and Oia, as well as the cultural and historic attractions in those two communities you will also pass the Covent of Saint Nicholas, the Chapel of Saint Antony and the quirky Chapel of Prophet Elias, as well as the famous Skaros rock, which you can climb for some rewarding panoramic views.
A visit to one of Santorini's renowned wineries is a great idea in May as at any other time. When visiting the wineries, go for Aidini, Assyrtiko, and Athiri if you are into whites, and Mandilaria and Mavrotragano if reds are more your thing. One of the best wineries to visit is Santo Wines near Pyrgos.
What to Do
Sunning yourself on the beach, swimming in the island's famously clear waters, indulging in a spot of sea kayaking or even taking a cruise around the island's coastline and huge, volcanic caldera are all wonderful activities in sunny May.
Before the fiercer heat of the summer, May's fresher weather is still suitable for hiking, and if you are going to do any one hike then that from Fira to Oia, along the clifftops with the azure Aegean Sea below, is the not-to-be-missed walk. A cluster of chapels, convents, and viewpoints along the way making it interesting as well as scenic.
International Workers Day (Protomagia, or May Day): The “worker’s holiday” on May 1st is an important part of the Greek calendar, and many businesses close. Whilst Athens hosts a huge rally, on Santorini it's just a day for relaxing with family and friends and generally also celebrating the arrival of spring. Wreaths of flowers are often hung in houses.
Feast day of St. Theodosia May 29. Celebrated in Akrotiri