Turkish climate can vary depending on the diverse topography and latitude.

Aegean and Mediterranean coastal areas enjoy the typical Mediterranean climate. There is almost no drop of rain during sunny and hot summer (May to October). Winters are rainy in these regions, while it very rarely snows if any, with the exception of mountainous areas higher than 2000 metres of these regions, which get quite heavy snowfall.

The region around the Sea of Marmara, including Istanbul, also has some kind of Mediterranean climate, but it can rain, albeit a little, during summer (as showers which tend to last for 15-20 minutes) and winters are colder. Snow is usual, although it doesn’t stay on the ground for long and limited to only a few days every winter.

Black Sea region has a subtropical oceanic climate in the east (thanks to the protective shield effect of Caucasus mountains), and a colder oceanic climate in the west. In the eastern parts of this region, it heavily rains during any season. The temperature seldom drops below +5 C, so it seldom snows in the coast, though mountains are as snowy as it is expected to be, there are even glaciers around the year in the highest zones. Summers in the western parts of this region are hotter, and less rainy and snow is not an unusual event.

Most of the coastal areas have a high level of relative humidity during most of the year which makes hot weather be felt hotter and cold weather be felt colder than it actually is.

Inner areas generally have hot summers (though the nights are cool enough to make one who’s wearing only a thin t-shirt uncomfortable outdoors) and cold and snowy winters. The more eastern the location is, the colder the winters are, the heavier the snow is. The northeastern part (around Erzurum and Kars) is the only inland area which has cool and rainy summers.

The southeastern region near the Syrian border has a desert-like climate, temperature is constantly above 40 C during summers with no rain. Snowfall is occasional in winters.

 

Source: (Wikitravel)