Flexi Says: Air temperature determines which type of precipitation falls. Rain falls if the air temperature is above freezing (0° C or 32° F). Frozen precipitation falls if the air or ground is below freezing. Frozen precipitation may fall as snow, sleet, or freezing rain. Snow falls when water vapor condenses as ice crystals. the air temperature is below freezing all the way to the ground, so the ice crystals remain frozen. They fall as snowflakes.