. Although the variation of monthly mean wind speed may slightly differ from year to year, it can be clearly observed that the mean wind speed drops abruptly from 3.58 m/s in January to 2.63 m/s in April During the period from April to August, the mean wind speed remains relatively stable around 2.6 m/s to 2.7 m/s. Afterwards, due to the approaching of the cold air mass from the North, it starts to increase from 2.6 m/s in August to 3.88 m/s in December.