Wind speed in km/h is indicated at different levels for a seven day period. Levels are selected at 50 hPa (mb) intervals, to reflect the closest level to the summit and below. Pressure has a relative correspondence to altitude, depending on atmospheric conditions. The equivalent height level is given in bracket and represent the average over the chart period. The bottom chart is the geopotential at the given pressure level, this is the actual correspondence between altitude and pressure. The altitude of the wind speed at any level will be roughly parallel to the geopotential line.
The wind speed is marked red above 60 km/h. This is an arbitrary threshold. 60 km/h is rather windy at high altitude, it may be OK on easy ground but it can make progress impossible on more technical routes.