In rare years, the warmth and pleasantness of a good November will stretch into early December.
Usually, however, the weather is chilly throughout the country, though milder along the Mediterranean coast.
In Istanbul, many days will be cloudy, with rain. You will probably enjoy some brisk, chill, sunny days as well. It is unusual to have frost in the city, and any dusting of snow—very pretty!—soon melts.
You must expect some rain, perhaps heavy, anywhere in Turkey. In Central Anatolia and eastern Turkey, there will most probably be some snow, particularly at the higher elevations (although in 2008, global warming seems to have melted the snowcap on the volcanic peak of Mount Erciyes in Cappadocia for the first time in living memory.)
Along the Aegean and Mediterranean coasts, snow is very unlikely. In the mountains of eastern Turkey, there will certainly be snow, sometimes closing roads.
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