Peter Craig, National Park Service · Public domain · Wikimedia Commons
Volcanic doublet in Samoan Islands, American Samoa
Ofu-Olosega is a volcano in United States. Its summit stands 639 m above sea level. Its prominence — how far it rises above the highest saddle linking it to a taller summit — is 639 m.
From the lowest point within 5 km (-5 m), it rises 644 m. The steepest side is the north face: 33° on average over the first kilometre. In places the ground near the top reaches 69° — terrain for climbers, not walkers.
The nearest town is Ofu, 7 km away at 4 m: 635 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
3.8/10
Difficulty to the top
Hike
Most path sections around the top are T1 on the SAC hiking scale.
Indicative only — never a safety assessment. Conditions change: ask local guides and check the forecast.
Ski score
—
No ski runs within 12 km in OpenStreetMap.
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
In a normal year there is no snow on this mountain, not even at the summit.
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 March afternoon the summit reaches about 25 °C; on August nights it falls to about 24 °C. Afternoons at the top are above freezing in every month of the average year. In March the 0 °C line climbs to about 5,720 m, above the summit: the top thaws on an average afternoon. Across the region, August is the driest month (60 mm) and January the wettest (273 mm).
| Month | Summit high °C | Summit low °C | Ofu high °C | 0 °C line (m) | Rain & snow (mm) | Wet days | Sun h/day |
|---|---|---|---|---|---|---|---|
| January | 25 | 24 | 28 | 5,700 | 273 | 25 | 6.8 |
| February | 25 | 25 | 28 | 5,700 | 253 | 22 | 6.9 |
| March | 25 | 25 | 29 | 5,720 | 168 | 24 | 7.7 |
| April | 25 | 25 | 29 | 5,720 | 172 | 22 | 7.4 |
| May | 25 | 25 | 28 | 5,700 | 130 | 20 | 7.1 |
| June | 25 | 24 | 28 | 5,620 | 80 | 16 | 7.3 |
| July | 24 | 24 | 28 | 5,500 | 75 | 15 | 7.4 |
| August | 24 | 24 | 27 | 5,480 | 60 | 14 | 8.1 |
| September | 24 | 24 | 28 | 5,500 | 86 | 16 | 8.4 |
| October | 25 | 24 | 28 | 5,560 | 136 | 21 | 8.2 |
| November | 25 | 24 | 28 | 5,640 | 216 | 24 | 7.5 |
| December | 25 | 24 | 28 | 5,680 | 246 | 24 | 7.1 |
Estimate: the NASA POWER climate of a ~55 km cell (average height 2 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 3× 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.
8 path sections within 5 km, by SAC hiking scale (T1 easy walk … T6 difficult alpine).
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 | 25 | 25 | 25 | 25 | 25 | 25 | 24 | 24 | 24 | 25 | 25 | 25 |
| 2020 | ±0.0 | −0.2 | +0.1 | +0.5 | +0.7 | +0.3 | +0.5 | +0.4 | +0.3 | +0.4 | −0.1 | −0.3 |
| 2021 | −0.2 | −0.4 | −0.3 | −0.2 | ±0.0 | −0.1 | +0.2 | ±0.0 | +0.1 | ±0.0 | −0.2 | −0.4 |
| 2022 | +0.1 | −0.7 | −0.4 | −0.2 | −0.3 | −0.1 | ±0.0 | −0.5 | −0.3 | −0.3 | −0.4 | −0.3 |
| 2023 | −0.5 | −0.3 | ±0.0 | +0.3 | +0.2 | +0.2 | +0.5 | +0.7 | +0.1 | +0.2 | +0.3 | +0.2 |
| 2024 | +0.9 | +0.8 | +1.1 | +1.4 | +1.1 | +0.3 | +0.2 | −0.4 | +0.2 | +0.2 | +0.1 | +0.5 |
| 2025 | +0.4 | +0.3 | +0.2 | +0.4 | +0.3 | +0.1 | +0.2 | +0.3 | −0.3 | +0.3 | −0.3 | +0.2 |
+1 warmer than usual −1 cooler than usual
Nearby
| Names, elevation, prominence | Wikidata (Q1631727) · 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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