Photo from the Mt. Fuji (altitude 2800m)The opening of the Mt. Fuji is July to August, summer season in Japan, but Mt. Fuji is very cold as if it’s like almost winter.
The average temperature of the summit in 2006 was 5.2℃(41.36゜F) in July, 6.9℃(44.42゜F) in August. Also you should know that the lowest temperature in recorded history was –4.3℃(24.25゜F). The average wind velocity of the summit is 7.3m in August. Regularly, it is said that by 1m wind speed, the feeling temperature fells 1℃(33.79゜F). Hence, take the average temperature record in August 2006 for example, the feeling temperature at the summit of Mt. Fuji becomes –0.4℃(24.25゜F). 
If you want to see the sunrize(A.M.4:00~5:00) from the top, it means that the temperature becomes colder. Therefore, you need to bring a fleece jacket or down jacket which protect you from cold winds.
data from Japan Meteorological Agency see all data?(1932~2009)
