A dramatic increase in rainy weather (average rainfall is at 3.9 inches/100 ml this month) and a slump in average daily hours of sunshine (just four) means there is no dressing up December in Santorini weather-wise. The island is mild or cool at best, with an increase in prolonged bursts of rain.
One positive, bizarrely, is the average temperature: being at the very beginning of Greek winter, it's not as cold on average in December as in any of the following three months, with 52-61°F/ 11-16°C the expected ranges right now. Nor is water temperature by any means at its lowest: in fact, with 17°C expected for the sea this month, it's warmer in the water than any month until May.
For more on weather this month, see Greece in December: Travel Tips, Weather, & More.
Crowds & Costs
December, as part of the winter season and because of its comparatively poor weather, does not see many tourists: indeed, compared to just two months ago, tourist levels have dropped right off. But such is the popularity of the island that a few visitors do still come, and are often very pleased with what they find: the majority of the sights still open and just without dozens of people in the background.
Costs have plummeted too: those accommodations that might seem unaffordable in the summer are suddenly affordable, such as the island's lovely cave villas and apartments.
Where to Go
Concentrate your sight-seeing on Fira and Oia this month, as poorer weather makes cultural sights, from museums to archaeological sights, as well as restaurant and hotel time, much more appealing. In Fira the town's cathedral and beautiful churches, or its museums, the Archaeological Museum of Thera, Museum of Prehistoric Thera and, just outside, Koutsoyannopoulos Wine Museum.
Oia, meanwhile, is one of the most photographed places anywhere in Greece for a reason. Some outstanding architecture in this little community, from the windmill and castle to the Naval Museum, housed in a beautiful former sea captain's house, are typical of the white-washed walls and blue-painted domes, doorways, and windows for which the town as a whole is famous. There are other photogenic smaller villages worthy of your time as well this month, such as Pyrgos or Megalochori, both with excellent viewpoints and a charming but time-lost feel.
And definitely sample some of the island's wine: when visiting one or more of the several renowned 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. In December's chillier weather, you might also appreciate a trip to the Nea Kameni hot mineral springs.
For a longer excursion, visit the remains of the ancient Minoan city of Akrotiri in the island's southwest. Sometimes referred to as the “Pompeii of the Aegean” and one of the key archaeological sites of the Greek islands, Akrotiri’s ruins include pottery, frescoes, and a complex drainage system illustrating how advanced this civilization was for its time.
What to Do
Cultural activities will feature heavily in your itinerary in Santorini in December: wandering around an archaeological site, perhaps, or discovering more about Santorini's storied past at a museum in Fira or Oia.
In this cooler weather, hiking can also be a good option. Try the challenging eight-mile hike between Fira and Oia, a special if strenuous introduction to island hiking. It should take you about 2.5 to 5 hours, depending on your fitness level and speed, and includes stops along the way, like quaint Ekklisia Profitis Ilias church. Vistas from the clifftops along the way will allow you to gaze down at the caldera this entire side of the island forms, ever since Santorini was blown apart by a huge eruption millennia ago.
Watching the sunset, what with the low winter sun, can be an absolutely spectacular experience, with Oia one of the best places for this activity, along with Akrotiri Lighthouse near Akrotiri. December's less appealing weather makes it more tempting to discover Santorini's dining scene—one of the best on any Greek island. Don't pass over a meal at clifftop fine dining experience Lauda, in Oia.
Several saints' days this month present good opportunities for observing local religious customs (see below).
Feast of St. Nicholas. On December 6, islanders head to church for ceremonies and festivals to honor St. Nicholas, patron saint of sailors.
Feast day of St Anne. December 9. Celebrated in the village of Vothonos.
Feast day of St Spyridon. December 12. Celebrated in Pyrgos, Emporio, and Oia.
Christmas Day. Second in importance to Easter in the Greek Orthodox calendar, December 25 is celebrated as elsewhere in Europe, with church services, street caroling, and family parties; and every town will be festooned with traditional decorations.
New Year’s Eve. Santorini's settlements launch fireworks, just as towns throughout Greece do. Children carol in the streets, and it’s a great pretext for parties.
Traveling to Santorini in December? Check out this great itinerary.
History & Culture in Athens and Santorini - 7 Days. Get to know ancient Athens and get a taste of island life on Santorini with this weeklong itinerary. Sample volcanic wine varietals in centuries-old vineyards, take a mythological tour of the capital, take a cooking class based on ancient Greek culinary methods, and more.