How Fast Do Raindrops Fall?

Gravity speeds a drop up at first

A drop released in a cloud accelerates downward because gravity pulls it toward Earth. As it moves faster, it pushes through more air and experiences greater drag. Eventually, drag can balance the downward force of gravity, leaving the drop to fall at a nearly steady terminal speed. [1]

Bigger drops generally fall faster

NASA’s Global Precipitation Measurement mission notes that terminal speed increases with drop size and reaches about 10 meters per second for the largest raindrops. Very tiny cloud droplets fall much more slowly. Large drops also tend to flatten and break apart, so real raindrops are not perfect spheres. [2]

Wind changes what reaches the ground

Terminal speed describes a drop’s motion relative to still air. In a storm, vertical drafts and horizontal winds can carry drops faster, slower, or sideways. This is why a single speed cannot describe every raindrop or every rainfall event.

A terminal speed is not one speed for all rain

Terminal speed depends on the drop’s size and shape and on the density of the surrounding air. A drop can also be carried by an updraft, so its speed relative to the ground may differ from its speed through the air.

That is why weather instruments and precipitation researchers measure distributions of drop sizes rather than assigning every raindrop a single velocity. The approximate maximum in still air is useful for scale, not a prediction of the speed of every drop in a storm.