午後から雨風強まる。早めの行動で下山を

Tateyama (Oyama) began with a light overcast this morning, but weather conditions are expected to deteriorate rapidly in the afternoon. As of 7:30 AM, the summit registers 7.1 degrees Celsius with a wind speed of 0.5 meters per second and visibility of 2.2 kilometers, four degrees colder than Murodo at the base. Light overcast will persist until around 9:00 AM, but by noon, strong drizzle is anticipated, transitioning to full rain by 3:00 PM.

Temperatures will drop to 5.4 degrees Celsius in the afternoon, accompanied by strengthening winds. Gusts are expected to reach 5.7 meters per second after 3:00 PM, potentially exceeding 13 meters per second overnight. This combination of wind and rain will cause the felt temperature to drop to approximately minus 1.4 degrees Celsius by 3:00 PM, significantly increasing the risk of hypothermia in this 3000-meter class mountain. The route from Murodo via Ichinokoshi to Oyama will become slippery due to wet rocks from the rainfall, requiring particular caution against falling rocks from Ichinokoshi.

The ground, currently exposed rock with no snow cover, will become wet and muddy with the rain. Essential gear includes waterproof and breathable rainwear (jacket and pants), and a mid-layer of warm clothing such as fleece or a light down jacket. Gloves and a hat are also mandatory. Given the certain deterioration of weather this afternoon, those aiming for the summit should start early and plan to begin their descent by noon at the latest. Avoiding risky endeavors and waiting for improved weather is a wise decision.