The great red spot is perhaps the Jupiter’s most recognisable feature. It’s a massive storm system that circles the planet’s southern hemisphere. Rather like an Earthly hurricane, the storm is relatively calm at the centre, but the outlying winds can reach speeds of 270-425 mph (430-680 km/h). It is also huge, encompassing an area twice the size of the Earth.
Source: https://www.space.com/jupiter-great-red-spot.html