Like everywhere else in the world, Greece has been affected by climate change, which guarantees unpredictable weather; sometimes periods that are expected to be sizzling hot will suffer rainfall and wind and vice versa.
Nevertheless, in general from early May to early June, the weather is sunny and warm and the sea is still a bit chilly for swimming. From mid-June until the end of August, the weather goes through quite a sweeping change and can become very hot, although the waters of the Aegean can prove sufficiently refreshing. In September the weather begins to mellow considerably, and by mid-October is usually at its warmth limit for swimming, although sunshine can continue throughout the year on and off. Between November and March these islands can make for an enjoyable trip; unlike the holiday-oriented islands there are enough restaurants, museums, and sites open to keep visitors happy, though the weather can make ferries unreliable.