霧晴れゆく夏の山。湿潤な足元に注意

This morning, Niseko Hirafu summit is cloudy with visibility less than 1km. Humidity is extremely high at 99%, and ridge lines are covered in fog, creating whiteout conditions. While the base is 20.6°C, the summit is 14.6°C, approximately 6°C cooler. There is a slight chance of light drizzle until around 9 AM, but the weather is expected to improve rapidly thereafter, becoming clear by noon. Temperatures are also forecast to rise to nearly 20°C with this improvement.

Today's ground conditions will remain damp due to the morning fog and high humidity. Especially the approaches to tree run areas and around gully terrain may be muddy. Expect many slippery sections. There is no snow cover, so crampons or microspikes are not necessary. Carry rain gear as a precaution, and although the wind is light, a thin insulating layer is needed for temperature changes when venturing onto the ridges.

The feels-like temperature at the summit will be around 15°C in the morning, rising to nearly 20°C during the day. An appropriate layering system would include a quick-drying base layer, a fleece or thin softshell as a mid-layer, and windproof/waterproof rainwear as an outer layer. The risks of strong winds and thunderstorms are low, but extreme caution is advised to prevent falls or slips on the wet ground. It would be safer to commence your activity in the afternoon, awaiting improved visibility.