When to fly to France
There really is no bad time to take cheap flights to France, but the best time to go really depends on what you want to do when you get there.
Mid-May to September (particularly July and August), the end of October, Christmas, February, and Easter are the high season times in France. These basically cover the school holidays when the French holiday and tourists from around Europe descend on the country too.
November–February is the low season in the cities and at the beaches, however this is high season for skiers and snowboarders.
(prices quotes are from London)