What is the typical speed of the fast solar wind in km/s?

The typical speed of the fast solar wind is about 750 km/s.

Solar wind is a continuous stream of charged particles flowing outward from the Sun’s corona. It has two broad regimes: slow solar wind, commonly around 400 km/s, and fast solar wind, which typically reaches about 750 km/s near Earth’s orbit. Actual measurements vary with location and solar activity.

Fast solar wind usually emerges from coronal holes, regions where the Sun’s magnetic field opens into space. These open field lines allow plasma to escape more freely than plasma trapped in closed magnetic loops. Fast wind is generally less dense and more strongly organized by Alfvénic magnetic fluctuations than slow wind.

When a fast stream catches a slower stream ahead of it, the interaction compresses the plasma and magnetic field. These stream-interaction regions can produce recurring geomagnetic disturbances and auroras. The solar wind also carries the Sun’s magnetic field outward, forming the interplanetary magnetic field and contributing to the Parker spiral as the Sun rotates.