Winds determine a balloon's direction. Balloonists can steer a balloon, to a limited extent, by adjusting the balloon's altitude to make use of different wind speeds and directions. Sport hot-air balloons carry 20 to 45 galloons of propane in stainless steel fuel tanks. Balloons typically fly from treetop level all the way up to several thousand feet, depending on what the pilot is trying to accomplish. Aerostar hot air balloon is over 32,000 feet.
Winds are generally most favorable the first hours after sunrise and the last hours before sunset.
The sun's uneven heating of the earth's surface causes strong, variable winds. In the morning, it takes a few hours for the sun to heat the earth's surface enough to generate the thermal activity that creates wind. In the evening, the sun's intensity has diminished enough to reduce winds to acceptable flight levels. Ideal winds are 3 to 6 mph. There are two levels of balloon pilot ratings.