Frank Schulenburg · CC BY-SA 4.0 · Wikimedia Commons
Lava dome in the Cascade Range
Lassen Peak is a volcano in the California Cascades (United States). Its summit stands 3,189 m above sea level. Its prominence — how far it rises above the highest saddle linking it to a taller summit — is 1,594 m. It was first climbed in 1851.
From the lowest point within 5 km (1,879 m), it rises 1,310 m. The steepest side is the north-east face: 30° on average over the first kilometre. In places the ground near the top reaches 44° — terrain for climbers, not walkers.
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
6.5/10
Difficulty to the top
Hike
Most path sections around the top are T2 on the SAC hiking scale. Glaciers around the top.
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.
Plan your visit
Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.
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 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Summit3,189 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 up2,534 msnow from November to June | 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 | No snow | No snow | Snow on the ground all month | Snow on the ground all month |
Foot of the mountain1,879 msnow from December to April (some years 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 some of the time | No snow | No snow | No snow | No snow | No snow | Snow some of the time | 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 July afternoon the summit reaches about 20 °C; on January nights it falls to about -15 °C. In 5 months of the year it stays below freezing at the top even in the afternoon. In July the 0 °C line climbs to about 6,190 m, above the summit: the top thaws on an average afternoon. Across the region, July is the driest month (5 mm) and December the wettest (183 mm).
| Month | Summit high °C | Summit low °C | 0 °C line (m) | Rain & snow (mm) | Wet days | Sun h/day |
|---|---|---|---|---|---|---|
| January | -7 | -15 | 2,130 | 129 | 13 | 4.8 |
| February | -6 | -14 | 2,300 | 139 | 13 | 5.9 |
| March | -3 | -13 | 2,750 | 136 | 13 | 6.9 |
| April | 1 | -11 | 3,300 | 77 | 11 | 8.9 |
| May | 6 | -7 | 4,160 | 53 | 9 | 11.1 |
| June | 13 | -3 | 5,210 | 19 | 4 | 13.6 |
| July | 20 | 2 | 6,190 | 5 | 1 | 14.4 |
| August | 18 | 1 | 6,040 | 5 | 1 | 13.0 |
| September | 14 | -2 | 5,360 | 11 | 2 | 11.2 |
| October | 6 | -8 | 4,150 | 52 | 6 | 8.7 |
| November | -2 | -12 | 2,900 | 97 | 10 | 5.7 |
| December | -7 | -15 | 2,090 | 183 | 13 | 4.2 |
Estimate: the NASA POWER climate of a ~55 km cell (average height 1,700 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.
Nobles-Emigrant Trail, Mill Creek Falls Trail, Crumbaugh Lake Trail, Brokeoff Mountain Trail and 9 more
Mill Creek Falls Viewpoint, Upper Cascades Viewpoint, Kings Creek Falls Viewpoint, Chaos Crags and Jumbles Scenic Pull-out and 14 more
D-19, Manzanita Lake Campground, Summit Lake North, Summit Lake South and 1 more
Drakesbad Guest Ranch
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 | -7 | -6 | -3 | 1 | 6 | 13 | 20 | 18 | 14 | 6 | -2 | -7 |
| 2020 | ±0.0 | +2.9 | −1.2 | +2.4 | +0.6 | +0.3 | +0.8 | +1.6 | +2.4 | +4.7 | +0.2 | +1.8 |
| 2021 | +0.9 | +0.3 | −0.6 | +4.3 | +3.8 | +5.6 | +2.8 | ±0.0 | +0.9 | −2.9 | +1.2 | −0.4 |
| 2022 | +0.1 | +2.8 | +2.6 | −0.8 | −0.7 | +0.2 | +1.6 | +2.7 | +1.5 | +4.5 | −3.2 | −1.6 |
| 2023 | −1.9 | −1.1 | −5.5 | +0.4 | +0.6 | −1.6 | +1.7 | +0.3 | −2.1 | +0.8 | +1.2 | +3.2 |
| 2024 | +0.8 | −0.4 | −1.4 | +1.6 | +1.2 | +3.5 | +3.9 | −0.9 | +1.3 | +2.4 | −2.3 | +1.9 |
| 2025 | +1.5 | +0.2 | −0.5 | +2.2 | +2.0 | +3.6 | +0.3 | +1.3 | −0.2 | −0.9 | +2.6 | +4.5 |
+1 warmer than usual −1 cooler than usual
Nearby
| Names, elevation, prominence | Wikidata (Q859354) · 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.
The family
Same idea, other landscapes: field atlases built on open data, month by month, in seven languages.
beaches
Find your beach: sea temperature, sun and swimming month by month.Visit 
lakes
Every lake on Earth: water temperature, ice, depth and the shore.Coming soonVisit 
mountains
Every summit in 3D: summit weather, the 0 °C line, huts and trails.You are here
waterfalls
Every waterfall: height, flow month by month and when it roars.Coming soonVisit 
islands
Every island from the sea up: size, sea temperature, ferries and 3D.Coming soonVisit 
rivers
Every river from source to sea: the journey, the flow and the basin in numbers.Coming soonVisit 
