幌尻岳山頂は現在曇り、気温は4.4℃だが体感は1.7℃。山麓との気温差は大きく、稜線ではより厳しく感じる。日中は概ね曇りだが、15時頃から弱い霧雨が降り始め、夜にかけて断続的に続く見込み。降水量は少ないものの、気温は午後から急速に低下し、夜には氷点下となる。
【急激な気温低下】予報期間中に11℃の低下が見込まれる。15時以降の弱い霧雨と気温低下が重なると、体感はさらに冷え込む。特に額平川コースのような沢渡渉が多いルートでは、濡れた衣服での行動が低体温症に直結する。ベースレイヤーは速乾性、ミッドレイヤーはフリース、アウターは防水透湿性シェルを着用し、保温着として薄手のダウンジャケットなどを一枚多めに携行すること。行動中の急な冷え込みに備え、引き返しの判断は早めに行う必要がある。
地面は全体的にウェットから泥濘状態と推測される。積雪はほぼないが、日中の霧雨でぬかるみやすくなる。防水透湿性の雨具上下は必須装備。額平川コースの沢渡渉には沢靴や濡れても良いシューズを用意し、滑りにくい足元で慎重に渡渉すること。風速は比較的弱いが、日高の稜線は風が抜けるため、行動停止時には冷え込みに注意が必要。この時期、ヒグマの活動も活発なため、単独行動は避け、音を出しながら行動し、食料管理を徹底する。
北海道
幌尻岳
Mt. Poroshiri
2026年5月21日 07:24 更新
日中は霧雨と低温に注意。沢渡渉は慎重に
Cloudy with light drizzle expected this afternoon. Prepare for significant
現在の気象状況 — Current Conditions
▲ 山頂エリア (Summit)
気温 Temp
+4.4°C
風速 Wind
1.1m/s
E
天候 Weather
☁️ 曇り
体感 Feels Like
+1.7°C
▼ 登山口・山麓エリア (Base)
気温 Temp
+16°C
風速 Wind
0.5m/s
N
天候 Weather
☁️ 曇り
標高 Altitude
320m
山頂の3時間予報 — Summit Forecast
09:00
+7°C
2.1m/s
ENE
💧 0mm
(0%)
12:00
+8°C
1.4m/s
ENE
💧 0mm
(0%)
15:00
+6°C
1.8m/s
NE
💧 0.2mm
(24%)
18:00
+2°C
2.1m/s
E
💧 0.3mm
(57%)
21:00
0°C
2.3m/s
E
💧 0.2mm
(90%)
00:00
-2°C
1.5m/s
E
💧 0mm
(22%)
03:00
-4°C
0.9m/s
ENE
💧 0mm
(0%)
気象分析 — Analysis Report
日本語
コンディション概ね良好 — 通常の山岳安全対策を実施すること
English
Conditions generally good — Conduct standard mountain safety measures
The summit of Mt. Poroshiri is currently cloudy, with a temperature of 4.4°C, but feeling like 1.7°C. There is a significant temperature difference compared to the base, and it will feel harsher on the ridgelines. It is expected to remain cloudy for most of the day, but light drizzle will begin around 3 PM and continue intermittently into the night. Although precipitation amounts are low, temperatures will drop rapidly from the afternoon, falling below freezing by night.
A sharp temperature drop of 11°C is anticipated during the forecast period. With light drizzle and decreasing temperatures from 3 PM onwards, the perceived temperature will feel even colder. On routes like the Ekihiragawa Course, which involves numerous river crossings, wet clothing can directly lead to hypothermia. Wear a quick-drying base layer, a fleece mid-layer, and a waterproof and breathable shell as an outer layer. Carry an extra insulating layer, such as a light down jacket, to prepare for sudden drops in temperature during your activity. It is crucial to make an early decision to turn back if conditions worsen.
The ground is expected to be generally wet to muddy. There is almost no snow, but the daytime drizzle will make trails prone to becoming slick. Waterproof and breathable rain gear is essential equipment. For river crossings on the Ekihiragawa Course, prepare wading shoes or footwear that can get wet, and cross cautiously on the slippery terrain. While wind speeds are relatively low, the ridgelines of the Hidaka Mountains are exposed, so be mindful of the cold during breaks in activity. Bear activity is also high during this season, so avoid solo travel, make noise while moving, and manage food properly.
A sharp temperature drop of 11°C is anticipated during the forecast period. With light drizzle and decreasing temperatures from 3 PM onwards, the perceived temperature will feel even colder. On routes like the Ekihiragawa Course, which involves numerous river crossings, wet clothing can directly lead to hypothermia. Wear a quick-drying base layer, a fleece mid-layer, and a waterproof and breathable shell as an outer layer. Carry an extra insulating layer, such as a light down jacket, to prepare for sudden drops in temperature during your activity. It is crucial to make an early decision to turn back if conditions worsen.
The ground is expected to be generally wet to muddy. There is almost no snow, but the daytime drizzle will make trails prone to becoming slick. Waterproof and breathable rain gear is essential equipment. For river crossings on the Ekihiragawa Course, prepare wading shoes or footwear that can get wet, and cross cautiously on the slippery terrain. While wind speeds are relatively low, the ridgelines of the Hidaka Mountains are exposed, so be mindful of the cold during breaks in activity. Bear activity is also high during this season, so avoid solo travel, make noise while moving, and manage food properly.
山岳ガイド — Mountain Guide
概要 Overview
北海道沙流郡平取町・新冠郡新冠町・日高郡新ひだか町にまたがる標高2,053mの日高山脈の最高峰。「最も困難な百名山」と称される険峻な山で、沢渡渉と長距離アプローチが特徴。
特徴・地形 Features
山頂への一般ルートには二十数回の沢渡渉が含まれ、日高山脈特有の深い原生林を抜ける。山頂部はカール地形と高山植物群落が広がる。
ベストシーズン Best Season
7月〜9月中旬。沢渡渉のため増水期・残雪期は困難。9月以降は寒気で危険。
主要ルート Main Routes
額平川コース(最一般的・幌尻山荘経由)、新冠コース、戸蔦別経由。
注意点・危険箇所 Cautions
沢の急増水で渡渉不能となるケース多数。山荘予約必須・抽選制。ヒグマ密集地で対策必須。
アクセス Access
平取町振内地区からシャトルバスで額平川登山口へ(要予約)。マイカーアクセス制限あり。
※ 本ガイド情報は一般的な参考資料であり、最新の登山道状況・規制情報は各自治体・登山口の公式情報をご確認ください。