午前は快晴も午後は強い雪。冬山装備必須

Currently at 07:15, Mt. Fuji summit is clear with a temperature of -4.7°C, feeling like -8.6°C. While winds are calm, the summit is already exhibiting severe winter conditions, with a temperature difference of -15.8°C compared to the base. Clear skies are expected to continue through the morning, but clouds will start to gather around 12:00, turning into heavy snow by 15:00, and even heavier snow (5.81cm/3h) by 18:00. Temperatures will drop from around -1°C during the day to -6.5°C by evening, with wind chill values potentially falling below -10°C.

As an isolated peak, Mt. Fuji's exposed slopes above the tree line are highly susceptible to wind and cold. The afternoon snowfall and temperature drop significantly elevate the risk of hypothermia. The steep volcanic scree slopes, characteristic of routes like the Yoshida Trail and Fujinomiya Trail, will become unstable with fresh snow, increasing the danger of slips and falls. The automated risk assessment indicates "Enhanced Snowfall and Avalanche Alert," meaning increased avalanche risk due to poor visibility and new snow accumulation. Avoid steep slopes and wind-loaded areas in the afternoon.

Essential layering includes a quick-drying merino wool or synthetic base layer, a fleece or lightweight down mid-layer, and a waterproof/breathable hard shell jacket and pants. Waterproof gloves, a warm hat, a balaclava, and a headlamp are also crucial. While current snow depth is 0cm, temperatures will remain below freezing all day. With afternoon snowfall, carrying microspikes or crampons is recommended. Given the deteriorating weather and high hypothermia risk in the afternoon, it is advisable to plan an early return by midday or consider postponing your ascent altogether.