曇天穏やか。午後から雨天へ。早めの行動を

Mount Rishiri summit currently experiences cloudy conditions with a temperature of 14.2℃, feeling like 13.6℃. Winds are light, and visibility is good. There is an approximate 9℃ temperature difference between the summit and the base, so the perceived temperature will significantly drop with elevation gain. Cloudy skies are expected throughout the day, but weather conditions will deteriorate in the afternoon. Temperatures will rise to 17.2℃ by noon but drop to 15.3℃ by 3 PM. Maximum gusts of 8.9 m/s are anticipated at noon.

The ground is currently dry, but light rain is expected from 6 PM, intensifying to weak rain after 9 PM. Heavy showers are forecasted for late night, with temperatures dropping below 10℃. The fragile volcanic gravel above 9th station becomes very slippery when wet, increasing the risk of rockfall, especially on the Oshidomari Course directly below the summit. Carrying waterproof and breathable rain gear is essential. For layering, pack a quick-drying base layer, a light fleece or wind shell, and a waterproof-breathable outer shell.

The automated risk assessment highlights a rapid temperature drop of 6℃ during the forecast period. The combination of falling temperatures and rain from late afternoon significantly increases the risk of hypothermia. Plan to be active from morning to early afternoon, aiming to begin your descent by 3 PM at the latest. While the risk of lightning is low, be prepared for deteriorating weather in the afternoon and make early decisions to turn back if necessary.