Acceleration

Air resistance

Air temperature

Angle of throw

Change in mass through melting of snowball in flight

Change in mass through snow accumulating on snowball

Contents of snowball

Coreolis effect

Direction of movement of thrower

Forces

Gravity

Initial velocity

Obstacles

Point object

Precipitation

Reference frame

Shape of snowball

Snow temperature

Spin

Terrain

Throw style

Velocity of thrower

Wetness of snow

Wind