Just about everyone agrees that the best time to visit Greece is spring and early summer (mid-April to mid-June) or autumn (September to mid-October).
At those times of year, you'll avoid the summer high season, with its inflated prices, hordes of tourists, and high temperatures (heat waves with temps reaching 100°F/+40C are routine). In fact, unless you actually like scorching heat, crowds, and overbooked planes, ferry boats, and hotels, August is to be avoided. Summer drawbacks loom especially large if you plan on visiting some of the more popular islands, Mykonos and Santorini first and foremost among them.
In the spring, you’ll see more wildflowers than you could have imagined, and swim in a sea that’s a bit cool but more pleasant than you had hoped for. In the autumn, you will enjoy golden days with still-warm waters.
One drawback: Off-season there are fewer boats and flights to the islands, where some shops, hotels, and restaurants do not open until June and then close in October. During the off-season life comes to a standstill on many islands, or at least turns its back on tourism, and wintertime rains can dampen any romantic notions of lonely wandering in empty landscapes.
Something else to consider if you are coming to Greece in the spring: During Easter week, nearly every hotel room outside of Athens is booked well in advance by city dwellers who head to the country to celebrate Greece's most important holiday. Many sites and museums are closed Good Friday, Easter Saturday, and Easter Sunday, while many shops close on Good Friday and Easter Saturday. When St. George's Day (usually celebrated April 23) falls during Lent, it's celebrated on the Monday after Easter Sunday, which only prolongs the Easter break. The Feast of the Virgin on August 15 is another enormous holiday.
When Greeks talk about the weather these days, they say that everything is ano kato—upside down. Some things everyone agrees on: The winters can be chilly, sometimes with unusual bursts of warm weather and sometimes even snow in Athens. It can go from warm to downright numbing. Many buildings are not insulated, and the centrally controlled heating is often intermittent, making the cold season seem very long indeed.
Summers are dry and hot, sometimes reaching 110°F (43°C). As the saying goes, only mad dogs and Englishmen would venture out in the midday sun, hence the siesta between 3pm and 6pm. The seasonal north (Etesian) winds blow mid-July to mid-August, but it can get very windy anytime, temporarily halting ferry transport.
Every day in Greece is sacred to one or more saints. That means that every day, at least one saint is being celebrated, along with everyone named for that saint. Tiny chapels that are used only once a year are opened for a church service followed by all-day wining and dining. If you're lucky, you'll stumble on one of these celebrations.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.