NASA reports that a storm on Neptune produced winds of about 750 mph during a visit by Voyager 2 in 1989. Neptune gets little energy from the sun due to the vast distance that separates them, yet it is capable of producing winds three times stronger than those on Earth.
The 1989 mega storm on Neptune was large enough to envelop the Earth. NASA nicknamed it the "Great Dark Spot." The storm has since disappeared; however, two more large storms have since been seen by the Hubble Space Telescope. The fastest tornadic wind ever recorded on Earth was estimated to be about 302 mph in 1999.