- The optimum speed for a balloon flight is 4-6 miles per hour.
- The balloon is inflated with cold air using a fan. The fabric of the balloon is basically a giant sail and winds over 6 miles per hour can make it difficult to fill the balloon. The wind will cave the side of the balloon in and cause it to roll around and drag anything it may be attached to. This can damage the balloon and basket as well causing harm to participants.
- The wind has to be blowing in the right direction - the balloon can't be steered in a particular direction and so the pilot has to be sure it won't be blown into an area that could be unsafe or where there aren't any suitable landing sites. Unsuitable areas include: built-up areas; wooded areas; large bodies of water; and restricted air space.
- Once airborn, if the wind speed is less than 4 miles per hour, the balloon won't really go anywhere. If it is more than 6 miles per hour, it can be blown off course, over-reach the landing place, and will also need more space to land. The basket may bounce along the ground, eventually tipping over, before the balloon comes to a standstill. A balloon doesn't have brakes and relies on the friction caused between the basket and the ground to slow it down and bring it to a stop. The balloon will be travelling at whatever speed the wind is. The stronger the wind the more friction will need to be built to bring it to a standstill and the further the balloon will need to travel along the ground.
- Just because the wind seems ideal at ground level, doesn't mean it's not blowing a lot faster higher up. The pilot will not only check the wind speeds at ground level and at the level you will be flying at, but also wind speeds much higher up as these could drop to the flying level during the flight, or cause other problems such as turbulance.
- There must be no fronts in the area where the balloon is being launched and flown. Fronts usually come with a change in wind direction or increased wind speeds.
- Balloons do not fly at night or in fog.
- There needs to be at least 1-3 miles visibility depending on the area and the hazards and the terrain.
- Rain can damage the balloon as well as decreasing visibility.
- There must be no thunderstorms within 100 miles of the launch point.
- Thunderstorms present hazards to any type of aircraft, but balloons are affected most of all. A plane can turn around and fly away from a storm; a balloon will get sucked in to it.
- Not only is there the chance of lightning striking the balloon, but gusts of wind can occur up to 100 miles away from a storm.
- Hot air is lighter than cold air and so rises. The air inside the balloon is heated and this causes the balloon to rise up through the colder outside air. If it is very warm outside it may not be possible to heat the inside of the balloon to a temperature that is sufficiently higher than the outside temperature.
So there you have it. With the weather needing to be SO perfect, it's a wonder anyone ever get to go on a balloon flight at all.