Summer beach holidays in the Greek islands bring blue skies and almost guaranteed sunshine from June to September. Not so in the winter. The dominant feature of Greek Islands' weather in summer may be hot and dry summers – ideal for a summer holiday break – but the winters are cold and wet.
These conditions are typical of the whole Mediterranean, but in the Greek islands you can add some wide local variations.
On the Greek mainland the biggest variation is found between mountain regions in the north, the low-lying south-eastern area of the Aegean and the western region that includes the Ionian Islands.
In the Greek winter, low-pressure systems drift in from the North Atlantic bringing rain and lowering temperatures. The drop in pressure helps to draw in cold winds from the Balkans.
The same low-pressure systems can also draw in warmer winds from the south so this tends to keep winter temperatures generally above freezing, with an average January temperature range between 6°C in Thessaloniki and 10°C in Athens.
Winter snow may fall almost anywhere in Greece but it is rare in the islands and does not last long except in the mountainous areas. Cyclonic depressions in lower-lying ground to the west and to the south make for milder winter weather with little frost.
In the west the Ionian Islands will have plenty of rain, with snow in the western mainland mountains. In the east its a different story. The eastern mainland, shielded by mountains, gets little rain.
For comparison average annual rainfall in Corfu off the west coast is 1,300mm ( three times that of London) while Athens, in the south-east, gets just 406mmm.
In summer the influence of low-pressure systems is negligible, giving hot, dry weather and average sea-level temperatures of 27°C in July. Summer winds may moderate the heat in coastal areas and on the islands.
Any of the Greek Islands can be especially warm in October and November but this is most true of the southern islands such as Rhodes and Crete.
A remarkable feature of the Greek Island climate is the long hours of sunshine – from four to five hours a day in midwinter to as much as 14 hours a day in midsummer.
The spring and autumn are relatively short seasons in Greece and mark a brief interlude between winter rain and summer heat. The weather can be very changeable at these times of year but for those who suffer in the summer heat, the months of April and October can be the most enjoyable seasons in the Greek Islands