You may get a day of rain but it usually adds a little excitement. This is a time to go to the islands like Mykonos, Santorini, and Rhodes because most of the tourists are gone. November to March can be cold and rainy but it can also be like Indian Summer. Athens comes alive during these months and there is nothing like a night out in the city. The ruins which are dry and dusty in the summer are covered with Grass.
Easter is a very special time to be in Greece.
This year it is on the 15th of April. In the islands it is like high-season so book in advance because if you just show up you may not find a room. If you like hiking, skiing, mountain-climbing, rafting, kayaking or exploring the mainland by jeep, this is the time to do. Most people buy the phone cards that are usable in some of the phones some of the time if you don't mind waiting in line. Or you can call from your hotel for five times the normal rate.