快晴の午前も午後急変。稜線は冷たい霧雨

The summit of Mt. Fuji currently enjoys clear skies and excellent visibility this morning. Stable weather is expected to continue through the morning. The felt temperature at the summit is a chilly 0.6℃, making warm clothing essential even now. Exposed slopes above the tree line, such as those on the Yoshidaguchi and Fujinomiyaguchi routes, are currently dry due to the clear weather, but climbers must be prepared for a rapid change in conditions this afternoon.

Thin clouds will begin to appear around noon, with light drizzle expected by 3 PM. The temperature will drop to 1.7℃, with the felt temperature even lower. As indicated by the automated risk assessment, a sharp temperature drop of 10℃ is forecasted during the period. Hikers should carry an extra layer of insulation from the start in preparation for sudden changes during their ascent, and make early decisions to turn back if conditions deteriorate.

By 6 PM, the drizzle will turn to snow, and temperatures will fall below freezing. Overnight, temperatures could plunge to -5℃, with gusts up to 10 m/s expected by early tomorrow morning. The steep volcanic gravel slopes, currently dry, will become wet with the afternoon drizzle and potentially icy or thinly snow-covered with the overnight precipitation and freezing temperatures. Nighttime activity significantly increases the risk of hypothermia and slipping. The risk of lightning is low.

Essential layering includes a quick-drying base layer, a fleece or light down jacket as a mid-layer, and a waterproof and windproof shell as an outer layer. For those planning nighttime activity, a heavier down jacket, waterproof gloves, and a knit hat are also necessary. Ground conditions are dry this morning, but will become wet this afternoon, with potential for thin snow and ice overnight. Crampons are not required, but chain spikes might be useful on icy sections.