Substances like motor oil and honey have high viscosity, while gasoline and benzene are examples of low-viscosity liquids. The viscosity of air increases slightly as temperatures increase, but not enough to make a noticeable difference in drag. The density of the air changes with variations in the temperature, pressure, and humidity of the air. As the temperature increases, the air density decreases. Air is 12 percent less dense at 95 degrees Fahrenheit than it is at 30 degrees Fahrenheit, resulting in markedly less drag.
Density also decreases with a drop in air pressure.
As you move to higher altitudes, air pressure decreases significantly, about 3 percent for every 1000 feet of elevation.