With the highest average monthly rainfall (4.5 inches/115 ml), least daily hours of sunshine, and some of the coolest temperatures of the year, January in Santorini is not the best month weather-wise.
But despite this, temperatures remain mild or even high by European standards at this time of year, with 48-57°F (9-14°C) the average temperature: not too bad for sight-seeing or even hiking and cycling. The general pattern of mild weather is occasionally disrupted by sudden bursts of heavy rain or snow.
For more on weather this month, see Greece in January: Travel Tips, Weather, & More.
Crowds & Costs
January, as part of the winter season and because of its comparatively poor weather, does not see many tourists. But such is the popularity of the island that a few 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 are down too: those accommodations that might seem way above budget in the summer are suddenly affordable, such as the island's lovely cave villas and apartments.
Where to Go
Relaxing in the island's charming clifftop capital, Fira, should be high on the agenda this month. Explore the town's cathedral and beautiful churches, the Archaeological Museum of Thera and the Museum of Prehistoric Thera. Wander the picture-perfect steeply twisting streets of white-washed houses, with an umbrella in tow.
Or, explore Santorini's winemaking heritage, with the closest wineries being Santo Winery in Pyrgos as well as the Koutsoyannopoulos Wine Museum just a couple of miles outside Fira. What wine to try? Perhaps an Aidini, Assyrtiko or Athiri if you dig whites, and Mandilaria and Mavrotragano if reds are more your thing.
At this cold time of year, you might appreciate a trip to the Nea Kameni hot mineral springs or, for a longer excursion, visit the important remains of the ancient Minoan city of Akrotiri in the island's southwest.
What to Do
It's not a month for swimming or water-based activities, so January is largely a month for cultural and town or village-based activities.
Fira makes a good base in January. Here, many of the bars and restaurants remain open, making for a decent nightlife to compliment days that could be spent exploring architectural and archaeological sights such as Fira's stunning Greek orthodox cathedral, or the Minoan ruins of Akrotiri. If you are on Santorini for Epiphany (see below), you can also check out the rituals associated with this special day, including the 'Blessing of the Waters' ceremony.
Chilly and rain-prone the weather may be, but there are still dry spells even at this time of year, making decent hiking weather. Not for the faint of heart (or wobbly-legged), the eight-mile hike between Fira and Oia 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.
Clifftop views will allow you to gaze down at the caldera this entire side of the island forms. Contemplating the caldera's might, it's easier to understand how the entire island was blown apart in the Thera eruption several millennia ago.
See here for a sample 3-day itinerary on Santorini.
Epiphany January 6. This is one of the most important Greek Orthodox celebrations, celebrating the baptism of Jesus by John the Baptist. A special series of carols, the kalanda, are sung at this time. In Santorini, this also involves the 'Blessing of the Waters' ceremony in which a procession leads from the church to the sea, and a priest throws a cross into the waters. Young men then compete to dive and retrieve the cross—he who wins it is blessed with good luck for an entire year.