午前は快晴。午後から雨具必須

The current summit condition is clear with a temperature of 5.5°C and a feels-like temperature of 3.2°C. There is a significant temperature difference of over 15°C compared to the base, indicating an alpine climate even in the morning. While clear skies will persist through the morning, light drizzle is expected around noon, intensifying to substantial rain by 3 PM. This rain will turn the volcanic scree on major routes like Yoshida-guchi and Fujinomiya-guchi into wet and muddy conditions. Extreme caution is advised, especially during descent, due to slippery terrain. On the exposed slopes above the tree line, climbers will be continuously subjected to wind and rain.

No significant alert values were detected by the automatic risk assessment. However, climbers must be wary of the afternoon rain and the subsequent drop in perceived temperature. Despite it being the summer season, the daytime feels-like temperature will likely drop from around 3°C even further with the onset of rain, posing a risk of hypothermia. Essential layering includes a quick-drying base layer, a mid-layer such as fleece or light down, and a waterproof-breathable outer shell (top and bottom). Rain gear is mandatory, and a helmet is recommended on the volcanic scree trails prone to rockfall.

Rain is expected to cease after 6 PM, with mostly clear skies through the night. Nighttime temperatures will drop to around 4°C, necessitating ample cold weather gear for summit stays or night activities. As Japan's highest peak, the risk of altitude sickness should always be considered; if any symptoms arise, prompt descent is crucial.