How fast is a whirlwind in mph?

Answer 1

It varies depending on the type and intensity of the whirlwind. Steam devils probably produce winds no stronger than a few mph. Winds in dust devils are typically around 30 mph and usually do not go above 50 mph, though at least one dust devil had peak winds estimated at 75 mph. Fair-weather waterspouts may have winds in the range of 40 to 70 mph, usually no stronger.

Tornadoes, the strongest whirlwinds, outstrip them all. Most tornadoes are categorized as "weak" with peak estimated winds of 65 to 110 mph, but the destructive ones are generally much stronger. In the most extreme cases, small subvortices within a tornado can produce wind gusts to over 300 mph.