Greece has a Mediterranean climate with plenty of sunshine, mildtemperatures and a limited amount of rainfall. Due to the country's geographical position, its rugged relief and its distribution between the mainland and the sea, there is great variation in Greece's weather.
In summer, the dry hot days are cooled by seasonal winds called the meltemi, while mountainous regions have generally lower temperatures.
The winters are mild in lowland areas, with a minimum amount of snow and ice, yet, mountains are usually snow-covered. Moreover, a common phenomenon is the occurrence of different climactic conditions during the same season (for instance, mild heat in coastal areas and cool temperatures in mountainous regions).
The dominant condition of Greece's climate is the alternation between hot, dry summers and cold, damp winters typical of the Mediterranean.
But considerable local variation results from elevation and distance from the sea. Generally, continental influences are felt farther north and in the center of the mainland. The main climatic regions of Greece are the mainland mountains, Attica (the south easternmost part of the mainland) and the Aegean, the west including the Ionian Islands, and the continental northeast.
In winter low-pressure systems reach Greece from the North Atlantic, bringing rain and moderating temperatures but also drawing cold winds from the eastern Balkans over Macedonia and Thrace as they pass into the Aegean Sea. The same low-pressure systems also draw warmer winds from the south, creating an average January temperature differential of 4° C between Thessaloniki (6° C) and Athens (10° C).
Cyclonic depressions provide the lowlands of the west and the south with mild winters and little frost. Beginning in late fall and continuing through the winter, the Ionian Islands and the western mountains of the mainland receive abundant rain (snow at higher elevations) from the west, whereas the eastern mainland, shielded by the mountains, receives much less precipitation.
Thus the average annual rainfall of Corfu off the west coast is 1,300 millimeters; that of Athens on the southeastern mainland is only 406 millimeters.
In summer the influence of low-pressure systems is much less, allowing for hot, dry conditions and an average sea-level temperature of 27° C in July. Summer winds have a moderating effect along the coast, but very dry, hot winds have a parching effect that causes drought in the Aegean area. The Ionian and Aegean islands are especially warm in October and November.
Elevation has an appreciable effect on temperature and precipitation at all latitudes, however. At higher elevations in the interior, some rainfall occurs year-round, and higher mountains in the southern Peloponnesus and on Crete are snowcapped for several months of the year.
The mountains of Macedonia and Thrace have colder continental winters influenced by winds channeled through the river valleys from the north.