羊蹄快晴 風強く体感低い。防寒具を

Clear skies are expected to continue on Mount Yotei. However, strong winds persist near the summit, making the effective temperature significantly lower. The current summit temperature is 2.9℃, with an effective temperature of -2.5℃. There is a substantial temperature difference of over 10℃ between the summit and the base, a characteristic of this isolated peak. Throughout the daytime activity window, areas above the treeline (approximately 1400m) will be heavily impacted by wind.

With no snow cover and no precipitation, the ground is generally dry. However, as temperatures will drop below freezing overnight, there is a potential for frozen patches and ice, especially in shaded areas, wind-exposed spots, and around the summit crater rim. Therefore, carrying microspikes or light crampons is recommended as a precaution. Exposed rocky terrain is also prevalent.

The effective temperature at the summit is predicted to drop below -5℃ tonight, with gusts exceeding 20m/s. This poses a high risk of hypothermia. Essential layering includes a wicking base layer, a fleece or light down mid-layer, and a windproof and waterproof hard shell as an outer layer. Always carry extra insulating layers. As an isolated peak, Mount Yotei offers no shelter from the wind above the treeline. On long direct routes like the Hirafu or Makari trails, be especially cautious of the sharp drop in effective temperature and strong gusts once past the treeline. Exercise extreme caution around the summit crater rim due to the risk of losing balance and falling in strong winds.

Clear skies will continue into the night, but temperatures will remain below freezing, and gusts are forecast to exceed 20m/s. Any activity after sunset carries significantly increased risks due to expanding frozen areas and a further drop in effective temperature, so unnecessary night travel should be avoided.