Belonging to the Mediterranean basin, the island of Santorini is more or less characterized by Mediterranean climate. That is warm to hot, dry summers and mild to cool, wet winters.
However the distinct geographic position and the small size of the island are responsible for special microclimate conditions in Santorini.
The main characteristics of these special conditions are winds and humidity.
Since there are no particularly high land points (such as mountains) around, the island is subjected to strong winds throughout the whole year. Most commonly northwestern winds, called by the locals ‘maistros’ but also south winds or ‘ostria’ which are usually stronger than the north ones. An important characteristic of Santorini (as well as, of the whole Aegean Sea) is meltemia.
Meltemia are annual local north or northwestern winds which blow from May to September. Locals consider them to be a relief or even a blessing during the hot summer days. So don’t be surprised if while calmly enjoying the view on Caldera you hear a whistle from somewhere beyond your understanding. It’s just the typical sound of what we can only call ‘strong island breeze’.
On any part of the island, the distance from the sea cannot be greater than approximately 3km (1.8 miles). That is why the atmosphere can be extremely humid at any time, even during the hot summer months. Once again this can only be relieving in a hot summer night.
Other than winds and humidity, the year can be roughly separated to winter, spring, summer and autumn similarly to every other Mediterranean area
During autumn and winter (September-February), mean temperature is 12.5°C (54.5°F).
On the other hand, spring and summer mean temperature is 25°C (77°F), while it can reach even 38°C (100.4°F) during a hot summer morning.
Still, it should be noted that season separation is only rough; given that during September and October temperatures can be pretty high (20-25°C or 68°F-77°F) and weather conditions are more similar to summer or spring.
Irregularity of the rainfall can vary considerably from year to year, even within the same month. However precipitations, that are for the most part rainfalls, occur only during the winter-autumn period. Snowfalls are very unusual in Santorini; such ‘bizzare’ phenomena might occur here only once in a decade. Locals can assure you that there won’t be any precipitation during summertime and especially from May to September. If you experience summer rain in Santorini, then something serious must be going on with the planet climate.