These are the times when the air is most stable and will provide a safe, enjoyable ride. Flights generally last about an hour, depending on various conditions.
Ballooning is largely recreational in nature, thus many flights happen on weekends and holidays.
Balloons don't fly when there is a threat of thunderstorms in the area. There are other conditions that can affect the decision to fly or not to fly. These are meant to ensure a safe flight. Observing the colorful fall foliage from a hot air balloon is truly breathtaking. Balloon pilots are certified by the FAA, in the same manner as airplane pilots.