The short version: come in late April to early June, or September to late October. Mild days, long light, and balloons flying on most mornings.
The longer version depends on what you are here for.
Spring — April to June
The valleys are green, which they are not for most of the year, and the orchards around Avanos come into blossom. Days are warm without being punishing and the mornings are still cold enough that you will want a jacket in the balloon basket. Early April can still turn wet; by May it rarely does.
This is the best all-round window, and it is not a secret — book accommodation earlier than you think you need to.
Summer — July and August
Hot, dry and busy. Midday in the open valleys is genuinely uncomfortable, which pushes everything to early morning and late afternoon. The compensation is that flights very rarely cancel, and the underground cities hold a steady cool all day regardless of what the surface is doing.
If you come now, do the walking at dawn and treat the middle of the day as somebody else's problem.
Autumn — September to October
Our own favourite. The heat breaks, the light goes gold, and it is harvest — the vineyards are working and the wineries are at their most interesting. October mornings are cold and clear, which is exactly what a balloon wants.
Winter — November to March
Snow on the fairy chimneys is genuinely one of the sights of Turkey, and you will have the valleys close to yourself. The trade-off is real: flights cancel far more often, some days do not fly at all, and daylight is short. Come in winter for the landscape, and treat a balloon flight as a bonus rather than the plan.
One practical note
Whenever you come, keep a spare morning for the balloon. It is the single most useful thing you can do with your itinerary, and we say it in every conversation we have about dates. More on that in how many days you need.
See what there is to do, or send us your dates and we will tell you honestly what that time of year is like.