霧雨に濡れる羊蹄山 低体温症に厳重警戒

Yotei Summit area is experiencing light drizzle with an air temperature of 3.2°C and a felt temperature of 0.8°C. There is a significant temperature difference of over 10°C compared to the base, indicating increasingly severe conditions as one ascends. Light drizzle or drizzle will continue throughout the day, with a peak temperature of only 7.6°C around noon. However, high humidity and constant wetness will make the felt temperature even lower.

Above the treeline at 1400m, Yotei's exposed nature as an independent peak makes it susceptible to wind effects. Although winds are light today, the drizzle will rapidly sap body heat, posing a very high risk of hypothermia. Ground conditions are expected to be muddy all day, particularly on routes like Makari and Hirafu, where the soil becomes loose and slippery with elevation gain. Circumnavigating the summit crater, known as Okachi-meguri, also demands extreme caution against slipping on the wet crater rim. Visibility is currently 4.8km but could rapidly deteriorate due to the persistent drizzle.

Essential gear includes a moisture-wicking base layer, a fleece or similar mid-layer, and full waterproof rain gear (top and bottom). Waterproof gloves, a waterproof hat, and spare warm clothing are also crucial. Crampons or microspikes are not necessary, but trekking poles will be beneficial for navigating muddy sections.

Temperatures will drop further to the 2°C range after dusk. Therefore, an early descent before sunset is strongly recommended. While no prominent alerts have been detected for this period, mountain conditions are constantly changing, and personal judgment is paramount for safety.