The weather on Hydra is very healthy and sunny. During springtime, the temperatures are ideal, ranging from 15 to 25°C; it is the best period to visit the island, even if the weather may sometimes change suddenly, and the risk of rain is not impossible.
Summer on Hydra is hot and sunny, like in most of the places in Greece; temperatures range from 25 to 38°C and sometimes rise up to 40°C, during July and August. The sea temperature is of about 27°C, rainfall is very rare and humidity is low. Hot winds from the south blow slowly during August.
Autumn is also a very nice season to visit Hydra. The weather is still warm and bathing is a real pleasure because the temperature of the sea is still of about 25°C, from the extreme heat of the summer.
Winter is mild and temperatures rarely drop below 0 degrees. January and March are often sunny and warm, like a spring break in the middle of the winter. Snow is extremely rare and when it appears, it only covers the mountains and never settles.
All in all, visiting Hydra all year around is always a good idea!