The official climbing season is from July 1 to the end of August. According to Ministry of the Environment Government of Japan, about 321,000 people climbed up to the 8th stations between July 1 and August 31 in 2010. If you are interested, please read other climbers' stories.
Although all trails get crowded, it's best to climb Mt. Fuji during the official climbing season. The off season climb is discouraged due to the bad climate. Temperatures around the summit can drop below the freezing point all year round, including summer months. In addition, harsh, strong winds often blow in the mountain. Please be aware of weather changes and huge temperature differences between the foot of mountain and higher elevations and be prepared. For more weather information, please refer to the current temperature at the summit (Japanese site) by Japan Meteorological Agency and 6 Day Weather Forecast for Mount Fuji by Snow-Forecast.com.
There are mainly four climbing routes: Kawaguchiko-guchi/Yoshida-guchi route, Gotenba-guchi route, Fujinomiya-guchi route, and Subashiri-guchi route. Most people go to the 5th station (go-gome) of each trail by car or bus and start climbing from there. For detailed information about climbing routes and access, please refer to Climb Mt. Fuji by Fujiyoshida-city and Climbing Mt. Fuji by Fuji Kyuko Co.
It's advised to stay in the 5th stations for a while before starting to climb in order to allow your body to adjust to the altitude. Many climbers start climbing in the afternoon and get some sleep at a mountain hut. Then, they climb up to the summit at sunrise or climb through the night with flashlights to get to the summit before the sunrise. If you begin having the symptoms of altitude sickness, such as headache, nausea, or vomiting, it's important not to keep climbing. Please take a break or descend the mountain before it gets worse.
There are many mountain huts located between 5th stations to the summit. Drinks and food are available in the huts, but they are relatively expensive. Please
make sure to bring enough water and food. It usually costs about 5,000 yen to 7,000 yen to spend a night in a mountain hut. Since they get crowded, it's
recommended to make a reservation. Most of mountain huts in Mt. Fuji are open only during the official climbing season.
Mountain Huts Information:
Fujinomiya Route Mountain Huts List (Japanese version) by Mt. Fuji Fujinomiya-guchi Tozan Kumiai
Yoshida Guchi Mountain Huts List by Fujiyoshida-city
Mount Fuji's crater is surrounded by eight peaks. Walking around the crater is called ohachi-meguri. If you have the time and strength, try to go to the Kengamine peak. It's the highest point in Japan.
For more tips on climbing Mt. Fuji, please refer to How to Climb Mt. Fuji by Yama-Kei Publishers.