Balloons launch around sunrise and only when the wind allows. Flights are often cancelled, more often in winter, and a cancellation is usually announced early in the morning. There is no way to know weeks ahead which days will fly.
Summer usually brings more settled weather, though the heat arrives early in the day. Whatever the season, the wind can change overnight, and a calm evening does not guarantee a flying morning.
Spring, from April to June, and autumn, in September and October, are the most popular seasons, and hotels with good terraces book up early. Staying two or three nights gives you several chances. Winter mornings over snow can be striking when the balloons do fly, but plan for gaps.
Booking a balloon-view room
For travel in spring or autumn, book a hotel with a balloon view well ahead, especially if you want a room with its own balcony or window towards the launch fields. These rooms are few and sell first.
Choose a flexible rate if you can. It lets you adjust your dates or extend by a night once you know the forecast, which can make the difference between seeing the balloons and missing them.