一ノ越から雄山へ 濡れと低体温症に警戒

The summit of Mt. Tateyama (Oyama) is partly cloudy with a temperature of 5.4℃ and a felt temperature of 2.4℃, with minimal wind. Murodo base is also cloudy at 9.4℃, warmer than the summit, but significant temperature fluctuations are expected during the day, requiring careful attention to activity. While the morning is relatively calm, light drizzle is forecast to begin around noon, transitioning to rain by evening. Temperatures will drop to 2.8℃ by 3 PM, and rain will continue through the night with even lower temperatures, posing a very high risk of hypothermia due to wet and cold conditions.

Current snow depth is 69cm, but the snow is wet due to rising temperatures and precipitation. The route from Ichinokoshi to Oyama Summit features a mix of residual snow and exposed rocky sections, where wet rocks and damp snow surfaces are slippery. Particular caution is needed during descent. Carrying microspikes or crampons is recommended. A waterproof and breathable outer shell is essential. For layering, use a moisture-wicking base layer, and insulating mid-layers such as fleece or a light down jacket. Also, pack an additional down jacket for stops. Carry multiple pairs of gloves and hats, ready to change them immediately if they get wet, as this is crucial for safety.

Although the wind is light, the felt temperature will drop rapidly as the body gets wet from the drizzle. Exposure to wind on the ridge line can quickly deplete energy. If movement is delayed due to congestion, the risk of hypothermia increases further, so plan for an early start and aim to begin your descent by 2 PM at the latest for safety. Visibility is currently good but may deteriorate rapidly once the drizzle begins.