Atsushi Ueda · CC BY-SA 3.0 · Wikimedia Commons
Mountain in Nagano and Gifu Prefectures, Japan
Mount Ontake is a volcano in the Hida Mountains (Japan). Its summit stands 3,067 m above sea level. Its prominence — how far it rises above the highest saddle linking it to a taller summit — is 1,712 m.
From the lowest point within 5 km (1,484 m), it rises 1,583 m. The steepest side is the south-west face: 28° on average over the first kilometre. In places the ground near the top reaches 40° — terrain for climbers, not walkers.
The nearest town is Kiso, 20 km away at 755 m: 2,312 m below the summit.
Scores
Two scores out of 10, built only from open data — every part is shown. They describe what the mountain offers, not how safe it is.
Hiking & mountaineering
6.4/10
Difficulty to the top
Mountain walk
Estimated from the slope: OpenStreetMap has no graded paths near the top.
Indicative only — never a safety assessment. Conditions change: ask local guides and check the forecast.
Ski score
5.6/10
Runs by difficulty
Snow season on the slopes (estimate)
Around 1,255 m, in the middle of the ski area: snow from December to April.
10 lifts · 0 km cross-country
Ski (where OpenStreetMap has skiing within 12 km): up to 4 points for the length of downhill runs (300 km or more = 4), 1.5 for the number of lifts (40+), 1.5 for the vertical between lift stations (1,500 m) and 3 for the snow season — a month counts when the estimated mean temperature at the height of the ski area is −1 °C or lower and snow falls or lies there (NASA POWER, 2001–2020). Hiking & mountaineering: up to 2.5 for waymarked routes and paths, 1.5 for huts, 2 for the ascent from the valley (2,000 m), 1.5 for prominence (3,000 m), 1.5 for the season (months with summit afternoons above −5 °C) and 1 for via ferratas, climbing and glaciers. OpenStreetMap is built by volunteers: where few things are mapped, a score can be lower than reality.
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Snow
At the summit, snow from October to July. Month by month below, at different heights on the way up.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Summit3,067 msnow from October to July | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | No snow | No snow | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month |
Halfway up1,911 msnow from November to May | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | No snow | No snow | No snow | No snow | No snow | Snow on the ground all month | Snow on the ground all month |
Kiso755 msnow from December to March | Snow on the ground all month | Snow on the ground all month | Snow on the ground all month | No snow | No snow | No snow | No snow | No snow | No snow | No snow | No snow | Snow on the ground all month |
Estimate for a normal year: average temperature and precipitation from NASA POWER, carried to each height, in a simple model of snow building up and melting. In a given year snow can come earlier or stay longer. It does not replace the local snow and avalanche bulletin.
Summit weather
Not a forecast: long-term averages (1991–2020), carried up to the summit. The orange line is where an average afternoon reaches 0 °C; above the dashed blue line it freezes even at dawn.
On an average August afternoon the summit reaches about 12 °C; on January nights it falls to about -22 °C. In 6 months of the year it stays below freezing at the top even in the afternoon. In August the 0 °C line climbs to about 4,980 m, above the summit: the top thaws on an average afternoon. Across the region, February is the driest month (86 mm) and July the wettest (234 mm).
| Month | Summit high °C | Summit low °C | Kiso high °C | 0 °C line (m) | Rain & snow (mm) | Wet days | Sun h/day |
|---|---|---|---|---|---|---|---|
| January | -14 | -22 | 1 | 880 | 100 | 19 | 2.6 |
| February | -13 | -21 | 2 | 1,110 | 86 | 15 | 3.5 |
| March | -8 | -17 | 7 | 1,770 | 114 | 14 | 4.5 |
| April | -1 | -12 | 14 | 2,860 | 121 | 12 | 5.5 |
| May | 5 | -6 | 20 | 3,780 | 128 | 13 | 6.3 |
| June | 8 | -1 | 23 | 4,340 | 159 | 16 | 5.0 |
| July | 12 | 4 | 26 | 4,830 | 234 | 19 | 4.4 |
| August | 12 | 4 | 28 | 4,980 | 158 | 17 | 5.7 |
| September | 9 | 0 | 24 | 4,430 | 185 | 15 | 4.6 |
| October | 3 | -6 | 18 | 3,490 | 159 | 13 | 4.5 |
| November | -4 | -12 | 11 | 2,450 | 103 | 14 | 3.6 |
| December | -11 | -18 | 4 | 1,380 | 116 | 19 | 2.3 |
Estimate: the NASA POWER climate of a ~55 km cell (average height 1,184 m), adjusted to the summit by −6.5 °C per 1,000 m. Rain, wet days and sunshine are those of the region. Mountain weather changes fast — always check a local forecast. ★ = mildest months at the top.
Relief
Two cuts through the summit, 16 km long, from the 30 m Copernicus elevation model. Heights drawn 2× taller than lengths, so the shape can be seen.
Average slope of the first kilometre from the summit. The orange petal is the steepest side.
Around the mountain
Counted around the summit in OpenStreetMap, the map anyone can edit. The satellite plate shows 14 × 14 km.
N
5 km
Sentinel-2 cloudless 2016 (EOX, CC BY 4.0), 14 × 14 km, north up. Points © OpenStreetMap contributors.
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OpenStreetMap is built by volunteers: a low number may just mean nobody has mapped it yet. Places © OpenStreetMap contributors (ODbL).
Photos
Recent years
Afternoon high at the summit (estimate). The first row is the reference, the 1991–2020 average in °C; the years show only the difference.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1991–2020 average | -14 | -13 | -8 | -1 | 5 | 8 | 12 | 12 | 9 | 3 | -4 | -11 |
| 2020 | +3.5 | +2.1 | +2.6 | −2.6 | +0.4 | +1.1 | −2.0 | +1.2 | +0.3 | −0.8 | +1.3 | +0.3 |
| 2021 | +0.9 | +1.1 | +4.2 | +1.0 | −0.5 | +0.2 | +0.4 | −0.8 | −0.3 | +0.5 | ±0.0 | +0.6 |
| 2022 | −0.4 | −1.7 | +1.5 | +2.8 | −0.2 | +0.2 | +0.7 | −0.1 | +1.7 | −0.4 | +2.0 | −0.7 |
| 2023 | +1.0 | +1.3 | +5.3 | +1.8 | −0.2 | ±0.0 | +1.3 | +1.4 | +2.3 | −0.6 | +1.3 | +2.2 |
| 2024 | +2.1 | +3.2 | −0.7 | +3.8 | +0.8 | +0.2 | +0.9 | +1.4 | +2.6 | +3.1 | +1.7 | −0.7 |
| 2025 | +0.8 | −1.8 | +1.1 | +1.2 | +0.3 | +1.6 | +2.5 | +1.0 | +1.3 | +1.5 | +0.1 | +1.3 |
+1 warmer than usual −1 cooler than usual
| Names, elevation, prominence | Wikidata (Q1754806) · CC0 |
|---|---|
| Relief, 3D view, profiles | Copernicus DEM GLO-30 · © DLR e.V., © Airbus Defence and Space GmbH, Copernicus/ESA |
| Climate | NASA POWER, 1991–2020 · CC BY 4.0 |
| Around the mountain | © OpenStreetMap contributors · ODbL |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
Every figure is an average, an estimate or a count from a public dataset. Licences and methods: data sources.
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