利尻山 稜線は風強し。体感氷点下で低体温症警戒

The apparent temperature near the summit of Mount Rishiri is expected to range from approximately -7 to -11 degrees Celsius throughout the day. Wind speeds will hover around 10 meters per second, with gusts exceeding 24 meters per second at times. These are extremely dangerous wind conditions, and any ascent must be judged with the utmost caution. There is about a 10-degree Celsius temperature difference between the summit and the base, indicating increasing severity with altitude.

Mount Rishiri is an isolated peak in the Sea of Japan, and exposed ridges are heavily impacted by sea winds. Particularly on the Oshidomari Course and Kutsuugata Course, when reaching the fragile volcanic scree zone above the 9th station, strong winds can make it difficult to maintain balance. Visibility is currently good, but wind gusts will further lower the apparent temperature, and sudden dense fog from the sea should also be anticipated.

The ground is predominantly exposed rock with no significant snow cover. Although there is no precipitation, the combination of low temperatures and strong winds means that any wet surfaces could freeze. Appropriate cold-weather layering is essential. Wear a moisture-wicking base layer, a fleece or light down mid-layer, and a fully windproof and waterproof outer shell. Gloves, a hat, and a balaclava are also mandatory. Crampons or microspikes are not necessary due to the lack of snow, but careful foot placement is required to prevent slips.

The prevailing apparent temperatures pose a very high risk of hypothermia. Moving in strong winds rapidly depletes energy, so any unnecessary exposure should be avoided. Temperatures will remain near freezing after sunset, and winds will not diminish. Nighttime activity carries life-threatening risks, so plan to complete your descent in the early afternoon.