Best Time for Swimming and Suntanning: The warmest weather in the Greek islands is between June and September when it’s sunny, hot and the water is perfect for swimming. Water temperature heats throughout the summer months and is warmest in August and early September. Swimming in May and October is often possible but can’t be guaranteed.
Best Time for Sightseeing: If you’re visiting Santorini more for the sights, views, wineries, and food then you don’t need hot weather just warm pleasant weather. So the months of April, May, October, and early November (as well as June through September) are fine times for touring the sights. The weather is still warm by northern european standards though there can be rain and some warmer clothing should be packed.
Best Time for Saving Money: Hotels are much cheaper in the low season (December to March) and shoulder season (April, May, October and November) than in the summer months. Transportation, food, and drink prices tend not to vary much by season. If you want good weather but cheap hotels then late May, early June, late September, or early October are the great times. There are no guarantees but the first three weeks of October can often surprise visitors with great weather.
High Season (late June to early September): Hot, sunny weather with lots of people – but never so many that it’s unenjoyable. Prices are at their peak. Sea water at its warmest and best for swimming. Ferries and flights run with the greatest frequency. If you’re in Greece for the nightlife then this is the time to visit.
Shoulder Season (May and June, September and October): Great weather. Sunny and warm but not blazingly hot like the summer. Tourists are many but it’s never crowded. Everything is open and ferries are running nearly all of their routes. The sea might not be warm enough for swimming in May and October.
Low Season (November to April): This is winter and that means gray skies, cool weather, and rain. Few hotels and restaurants are operating (but enough to get by). Ferries and flights have very limited schedules though there’ll be at least one a day going to Athens.
Santorini Weather by Month
Santorini temperature by month. The hottest and coldest months to visit.
Santorini Rain by month. The driest and rainest months of the year.
The best weather on Santorini is from June to September. July and August are the busiest months when hotels are full and restaurants are crowded. If you’re more interested in sightseeing, hiking, and great views then May and October are great months to visit.
January Weather on Santorini: Damp, cold, and windy (by Santorini standards). January is the rainiest month and one of the coldest. The island is very quiet with few tourists. Many restaurants and hotels are closed but you will always be able to find something open in Oia and Fira. The beach towns are completely shutdown. (Average Max Temperature: 14°C. Average Rainfall: 42mm.)
February Weather on Santorini: Much like January. February is Santorini’s coldest month. There is a little less rain than December and January (Average Max Temperature: 14°C. Average Rainfall: 35mm.)
March Weather on Santorini: A noticeable change occurs in March from the previous 3 months. There is less rain, more sun, and warmer temperatures. This can be a nice time to visit for hikers and sightseers but visitors should be prepared for some rain and cold nights. By the end of March most hotels and restaurants are open. (Average Max Temperature: 16°C. Average Rainfall: 32mm.)
April Weather on Santorini: A great month for hiking, sightseeing, and touring the wineries. On warm years it’s possible to have a few beach days at the end of the month. (Average Max Temperature: 19°C. Average Rainfall: 12mm.)
May Weather on Santorini: There are big differences between early May (when cool cloudy days can still be common) and late May (when the days are consistently sunny and warm). May is the month when the beach towns dust off the cob webs and open for business. (Average Max Temperature: 22°C. Average Rainfall: 7mm.)
June Weather on Santorini: June is a hot sunny month and the start of beach season when tourists arrive in large numbers. (Average Max Temperature: 26°C. Average Rainfall: 0.3mm.)
July Weather on Santorini: Hot and sunny. Along with August July is the busiest month on Santorini. Book rooms months at least 3 months in advance for July visits – especially for luxury hotels. (Average Max Temperature: 27°C. Average Rainfall: 0.9mm.)
August Weather on Santorini: Hot and sunny with occasional strong winds (called the meltemi) that can cancel ferries and catamarans. Book rooms at least 3 months in advance for August visits – especially for luxury hotels. (Average Max Temperature: 27°C. Average Rainfall: 0.4mm.)
September Weather on Santorini: Hot and sunny but cooling a little from August. The weather is similar to June but the water tends to be warmer as it heats over the summer months. Winds have died down. September is the best month to visit Santorini. Hotels are still very busy and can be fully booked months in advance. (Average Max Temperature: 25°C. Average Rainfall: 6mm.)
October Weather on Santorini: October is much like May but the weather is moving in the opposite direction. There is often a large difference between early October (when days can be hot and sunny) and late October – when you can find some cool rainy days and visits to the beach seem a distant memory. (Average Max Temperature: 22°C. Average Rainfall: 18mm.)
November Weather on Santorini: The cool and cloudy days of winter arrive in November. Early November can still see some warm days when a visit to the beach could be possible for the very brave. Almost all luxury hotels are closed by November 15. Oia and Fira stay moderately active until the final cruise ship of the season makes its visit (usually in mid to late November). (Average Max Temperature: 18°C. Average Rainfall: 44mm.)
December Weather on Santorini: Cool, cloudy, and rainy, though there are often stretches of sunny days. Fira is the hub of most activity during the winter as most other towns are completely shut down. Oia will have at least a few restaurants and hotels open as well. (Average Max Temperature: 15°C. Average Rainfall: 46mm.)
How long to spend on Santorini – You need 2 to 3 days minimum to get a feel for the island, see the top attractions, experience the sunset from a couple of different locations, and try some of the island’s great restaurants. You could easily fill a week with long walks, swimming and sunbathing, and more eating, clubbing, and dancing. If you have more than a week in Greece then I’d encourage you to spend 7 to 10 days on Santorini and then travel to a different island as there are so many great islands to see. You’d likely experience more by seeing Naxos, Paros, Ios, Mykonos, Crete, or Rhodes than staying in Santorini for a second week.