September is the bridge between summer and autumn on Santorini, although generally its weather patterns, temperatures, and rainfall are far more similar to the high season months of June, July and August. With average lows of 66°F/19°C and average highs of 79°F/26°C, this month is still very much beach weather, and this is backed up by a healthy ten average hours daily of sunshine and the joint-second hottest seawater temperatures of the year after August (73°F/23°C).
There are few downsides, but one is that 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, can still affect your plans in September. This is good because it injects some freshness into an otherwise sweltering warm season, but bad because it can make the sea rough.
For more on weather this month, see Greece in September: Travel Tips, Weather, & More.
Crowds & Costs
What crowds? The crowds of high season keep on falling away this month, and this means that Santorini is a far more enjoyable place to be overall with no tourists wandering into your photo frames, or taking up that table with the sea view you covet in the restaurant. As tourist numbers dwindle, you may find hotels will offer shoulder season rates or other deals. This is especially true at the end of September, after the conclusion of the Santorini International Music Festival (below).
Where to Go
Fira, the island's clifftop capital, should be on your radar for several reasons this month: aside from some fantastic museums showcasing the island's viticultural heritage (Koutsoyannopoulos Wine Museum) and archaeological heritage (the Archaeological Museum of Thera and the Museum of Prehistoric Thera), one of the most important festivals in the year is taking place right now: the Santorini International Music Festival.
Just outside Fira, Santorini's wineries await, in full color this month as the island's grape harvest continues. 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.
Other than that, keep concentrating your efforts on exploring Santorini's glorious beaches this month. There are some wonderful stretches of sand (and pebbles!) to discover. At Kamari, a black sand beach with a hotel sitting directly on the sand; at other sandy beaches with hotels such as Perissa and Perivolos and at striking Red Beach, comprised of small red stones and with beautiful crystalline water, you may not have the place totally to yourself. But at the more outlying beaches, like the long and lovely Baxedes Beach near Oia, you might just get some seaside time where it is just you, the beach and the sea.
The must-do longer excursion is, as ever, the important remains of the ancient Minoan city of Akrotiri in the island's southwest: this is one of the most significant archaeological sites in all the Greek islands.
What to Do
Lounge on the beach whilst soaking up the year's late summer sun, or swim in the azure and still-warm waters off the east coast. September is a fantastic time to try sea kayaking too, with several routes available: getting to see the volcanic, cave-riddled cliffs of the island from the water is a memorable experience.
On the west coast, catching a close-up view of Santorini's caldera, blown out by a colossal eruption millennia ago, is the big draw. You can see it up close on a catamaran cruise, or from the cliffs as part of a spectacular hike between island capital Fira and pretty Oia.
A trip to a winery should be on the cards for everyone: September is the time of the island's annual grape harvest, and a great time to see Santorini in all the color that this involves. And finally, should any changeable or rainy weather interrupt your trip, there are great museums to check out in Fira and Oia and archaeological sites like Akrotiri to visit.
Santorini International Music Festival. During the first three weeks of September, this is a program of classic, opera, chamber and tango music which has been going strong since 1978. Many internationally famous artists perform.
Ifestia. This one is all about the fireworks - and not just any fireworks. Recently moved to be a September event, this pyrotechnic display attempts to emulate the monumental volcanic eruptions of past millennia on the island (with all of the spectacle and, of course, none of the danger!)
Santorini Wine Tasting - Day Tour. This island tour begins in Oia, and continues with a trip up to the highest peak on Santorini. As you descend, stop at the medieval villages of Megalochori and Pyrgos, and the blue-domed church in Firostefani. The tour ends with a wine tasting where guests sample varietals dating back centuries, complemented by epic caldera views as the sun goes down.
Cultural Cyclades: Mykonos, Santorini, & More - 12 Days. Visit four distinct islands in Greece's most famous archipelago with this 12-day itinerary. Shop the glamorous boutiques of Mykonos, take a cooking workshop on cultural hotspot Naxos, experience village life on tiny Ios, and soak in the sun (and sunsets) of Santorini. Along the way, you'll enjoy lots of Greek history, glorious beach time, and pretty ferry rides across the Aegean sea.