Wind environment around a tall building is evaluated by the cumulative frequency of mean wind speed in the assessment criteria by Wind Engineering Institute. In the assessment criteria, mean wind speeds with the cumulative frequencies of 55% (55% wind speed) and 95%(95% wind speed) are shown as one of the assessment indices and it is stated that the 55% wind speed and 95% wind speed are equivalent to the yearly mean wind speed and the yearly mean of the daily maximum wind speed, respectively as the commentary. In addition, it is shown about a method to be based on an gust wind speed being converted by a gust factor.The authors calculate the yearly mean wind speed, the daily maximum wind speed, the yearly mean gust wind speed and the yearly mean of the daily maximum gust wind speed and compare them with the 55% wind speed and 95% wind speed. And the gust factors based on the mean wind speed and the gust wind speed are also examined. This paper reports the knowledge about the 55% wind velocity and the 95% wind velocity and also reports the wind environment assessment based on gust wind speed by the scale parameter ratio or the gust factor at the probability of exceedance of 36.8 %.