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Lassen Volcanic National Park

California · Established August 9, 1916

Boiling mud, a sleeping dome, and all four kinds of volcano in one park

Area: 106,589 acres
Established: August 9, 1916
Recreation visits: 504,777 / yr
State: California
Highest point: Lassen Peak, 10,457 ft (3,187 m)
Lowest point: Hot Springs Creek

Lassen Volcanic Weather Forecast

Loading the National Weather Service forecast for Lassen Volcanic…

Seven-day outlook at the park's reference point (40.493, -121.408). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Lassen Volcanic National Park

The Park

Lassen Volcanic National Park sits at the southern end of the Cascade Range in northeastern California, where the ground still hisses and bubbles. Boiling springs, mud pots, and steam vents fill the basins around Lassen Peak, a dome of volcanic rock that last erupted between 1914 and 1917, and the landscape around it holds examples of every major type of volcano found on Earth.

The park was established on August 9, 1916, while Lassen Peak was still active. Beyond its thermal areas it protects clear alpine lakes, flower-filled meadows, and forests of red fir and pine, all buried each winter under some of the deepest snowpack in California.

Geography

The park covers about 106,589 acres on a volcanic highland where the Cascade Range meets the Sierra Nevada and the Modoc Plateau. Lassen Peak rises near the western side of the park, with the eroded remnants of the ancient Brokeoff Volcano to its southwest and the Chaos Crags to its north. The main park highway curves around the peak, passing Sulphur Works, Lake Helen, and the Bumpass Hell trailhead before descending to Manzanita Lake.

East of the peak the land becomes a broad forested plateau of shield volcanoes, lava flows, and lakes, including Snag, Butte, and Juniper lakes, with Cinder Cone and the Fantastic Lava Beds in the northeast corner. Snowmelt from the high country feeds creeks that flow toward both the Sacramento and Feather rivers.

Landmarks

Lassen PeakVolcano · 10,457 ftOne of the largest lava domes on Earth, which erupted from 1914 to 1917.
Brokeoff MountainPeak · 9,235 ftThe highest remnant of Mount Tehama, a large stratovolcano that has been deeply eroded.
Bumpass HellAreaThe park's largest hydrothermal area, with boiling pools, fumaroles, and mud pots reaching about 198°F.
Chaos CragsVolcanoA cluster of dacite domes about 1,100 years old, fronted by the rockfall debris of Chaos Jumbles.
Cinder ConeVolcanoA symmetrical cone of loose cinders rising above the multicolored Painted Dunes and Fantastic Lava Beds.
Prospect PeakVolcanoA broad shield volcano rising above the forested plateau in the park's northeast.
Reading PeakPeakA volcanic peak east of Lassen Peak along the park's central high country.
Lake HelenLakeA deep blue lake at about 8,200 ft beneath Lassen Peak, one of the snowiest spots in California.
Manzanita LakeLakeA lake formed behind the Chaos Jumbles rockfall, offering classic reflections of Lassen Peak.
Butte LakeLakeIts shore is lined by the jagged edge of the Fantastic Lava Beds.
Snag LakeLakeA lake created when lava flows from Cinder Cone dammed a creek.

Geology

Lassen Volcanic National Park lies over the southern end of the Cascadia subduction zone, where the Gorda Plate sinks beneath North America and melts to feed volcanoes. The Lassen Volcanic Center has been active for about 825,000 years. Its early phase built the Rockland volcanic complex, which ended about 610,000 years ago in a violent eruption of rhyolite that scattered ash as far as Nevada and Idaho.

From about 600,000 to 400,000 years ago, eruptions of andesite built Mount Tehama, also called Brokeoff Volcano, a composite cone that may have stood around 11,000 feet tall. Hydrothermal activity softened its central core into clay, and glaciers and streams carved it away. Brokeoff Mountain, Mount Diller, and Mount Conard are the surviving rim, and Sulphur Works marks steam still escaping near its former heart.

A new phase of dacite eruptions followed on Tehama's northern flank. About 27,000 years ago thick, pasty lava squeezed up to form Lassen Peak, which rises about 1,800 feet above its surroundings. The Chaos Crags domes pushed up only about 1,100 years ago, and a later collapse of their flanks produced the rockfall field of Chaos Jumbles. In the park's northeast, Cinder Cone erupted in the mid-1600s, sending out the Fantastic Lava Beds. Then, on May 22, 1915, Lassen Peak's Great Explosion sent an ash column about 40,000 feet high, and lahars swept through what is now called the Devastated Area.

Deep time

About 825,000 years agoVolcanic activity begins at the Lassen Volcanic Center with the Rockland complex.
About 610,000 years agoA huge rhyolite eruption spreads ash across much of the western United States.
600,000 to 400,000 years agoMount Tehama (Brokeoff Volcano) builds a large andesite stratovolcano.
About 27,000 years agoLassen Peak rises as a massive dacite dome on Tehama's northern flank.
About 1,100 years agoThe Chaos Crags domes push up north of Lassen Peak.
Mid-1600sCinder Cone erupts, building its cone and the Fantastic Lava Beds.
May 22, 1915The Great Explosion of Lassen Peak sends ash about 40,000 ft into the sky.
June 1917Lassen Peak's eruptive episode comes to an end.

The rocks

Rockland volcanic complexAbout 825,000–609,000 years
The earliest domes and flows of the Lassen Volcanic Center, ending in a massive rhyolite eruption.
Brokeoff Volcano (Mount Tehama) andesiteAbout 600,000–400,000 years
Layered andesite lavas and ash of a collapsed stratovolcano exposed at Brokeoff Mountain.
Lassen Peak daciteAbout 27,000 years
Glassy, silica-rich lava forming the park's great plug dome.
Chaos Crags dacite domesAbout 1,100 years
The youngest domes in the park.
Chaos JumblesAt least 300 years
A rockfall avalanche deposit of dacite blocks covering about 2.5 square miles.
Fantastic Lava BedsMid-1600s
Blocky basaltic andesite flows from Cinder Cone that dammed Snag Lake.
1915 lahar deposits1915
Mudflow deposits of the Devastated Area on Lassen Peak's northeast side.

Trees, Plants & Ecosystems

805vascular plant species recorded

Mixed conifer forestAbout 5,300–6,500 ft
Ponderosa and Jeffrey pine, white fir, sugar pine, and incense-cedar grow on the lower slopes around the park's edges.
Red fir forestAbout 6,500–8,000 ft
Dense stands of California red fir thrive where heavy snowpack lingers into early summer.
Subalpine forest and meadowsAbout 7,500–9,000 ft
Mountain hemlock, whitebark pine, and wet meadows of corn lily and elephant's head surround high lakes.
Alpine fell fieldsAbove about 9,000 ft
Sparse cushion plants such as dwarf hulsea and pussypaws grow in loose volcanic rock on Lassen Peak.
Hydrothermal areasScattered
Hot, acidic soils around fumaroles and mud pots support heat-loving microbes and few plants.

Trees

California red firAbies magnificaThe signature tree of the snowy mid-elevation forest.
White firAbies concolorA common fir of lower, warmer slopes.
Jeffrey pinePinus jeffreyiIts bark smells of vanilla or butterscotch on warm days.
Ponderosa pinePinus ponderosaA tall pine of the park's lowest forests.
Sugar pinePinus lambertianaThe world's tallest pine species, with foot-long cones.
Lodgepole pinePinus contortaGrows in dense stands around meadows and lava plains.
Western white pinePinus monticolaFound on rocky slopes in the upper forest.
Mountain hemlockTsuga mertensianaDroops gracefully under snow near timberline.
Whitebark pinePinus albicaulisGrows as twisted, wind-shaped trees at the highest elevations.
Incense-cedarCalocedrus decurrensA fragrant, cinnamon-barked conifer of lower forests.
Quaking aspenPopulus tremuloidesClonal groves that turn gold in autumn near meadows.
Western juniperJuniperus occidentalisHardy, gnarled trees on dry, rocky volcanic ground.

Wildflowers, shrubs & other plants

Mountain pridePenstemon newberryiRose-pink flowers spilling over volcanic rock in early summer.
PussypawsCalyptridium umbellatumFuzzy pink flower heads on sandy, pumice-rich soils.
Dwarf hulseaHulsea nanaA tiny yellow daisy of high volcanic slopes, including Lassen Peak.
Woolly mule's-earsWyethia mollisBig yellow blooms and felted gray leaves on dry slopes.
California corn lilyVeratrum californicumA tall, leafy plant forming thick stands in wet meadows.
Elephant's headPedicularis groenlandicaPink flowers shaped like tiny elephant heads in boggy meadows.
Sulphur buckwheatEriogonum umbellatumBright yellow umbrellas of flowers on rocky ground.
Spreading phloxPhlox diffusaLow mats of white-to-pink flowers.
Crimson columbineAquilegia formosaRed-and-yellow nodding flowers visited by hummingbirds.
Greenleaf manzanitaArctostaphylos patulaA red-barked evergreen shrub common after fire.
Tobacco brushCeanothus velutinusA sticky, aromatic shrub of open slopes.
Bog laurelKalmia polifoliaPink cup-shaped flowers around subalpine lakes.
Lewis's monkeyflowerMimulus lewisiiRosy blooms along snowmelt streams.
Leopard lily (Shasta lily)Lilium pardalinumOrange spotted lilies in moist, shady spots.

Wildlife

58mammals
169birds
8reptiles
5amphibians
9fish

Mammals

American black bearUrsus americanusThe park's largest predator, often seen in meadows and forests.
Mule deerOdocoileus hemionusCommon in meadows at dawn and dusk.
CougarPuma concolorRarely seen, but present throughout the park.
American pikaOchotona princepsCalls from talus slopes near Lassen Peak and the Chaos Jumbles.
Golden-mantled ground squirrelCallospermophilus lateralisA striped squirrel common around trailheads and rocky areas.
Yellow-bellied marmotMarmota flaviventrisSuns itself on boulders in the high country.
American martenMartes americanaThe Sierra marten hunts in red fir forest.
Shadow chipmunkTamias senexOne of several chipmunk species in the park's forests.
Douglas squirrelTamiasciurus douglasiiA chattering conifer squirrel.
Mountain beaverAplodontia rufaA primitive rodent of moist, brushy stream banks.
Snowshoe hareLepus americanusTurns white in winter to match the deep snow.
PorcupineErethizon dorsatumFeeds on inner bark of conifers.
American beaverCastor canadensisFound along lower creeks and lakes.
Western long-eared myotisMyotis evotisOne of several bats hunting over meadows on summer nights.

Birds

Clark's nutcrackerNucifraga columbianaA loud gray corvid of the high whitebark pine zone.
Steller's jayCyanocitta stelleriA crested blue jay of campgrounds and forests.
Gray-crowned rosy-finchLeucosticte tephrocotisForages on snowfields near Lassen Peak.
Black-backed woodpeckerPicoides arcticusSeeks out burned forest to feed on beetle larvae.
White-headed woodpeckerPicoides albolarvatusA striking woodpecker of pine forests.
Williamson's sapsuckerSphyrapicus thyroideusA woodpecker of high conifer forests.
California spotted owlStrix occidentalisNests in dense, mature forest.
Bald eagleHaliaeetus leucocephalusOccasionally fishes at the park's larger lakes.
OspreyPandion haliaetusDives for fish at Manzanita and Butte lakes.
American dipperCinclus mexicanusForages underwater in rushing creeks.
Mountain chickadeePoecile gambeliA common, cheerful resident of conifer forests.
Western tanagerPiranga ludovicianaA red-headed, yellow-bodied summer visitor.
Sooty grouseDendragapus obscurusMales hoot from conifers in spring.
Townsend's solitaireMyadestes townsendiSings from treetops on rocky slopes.

Reptiles & amphibians

Western toadAnaxyrus boreasBreeds in shallow lakes and ponds.
Cascades frogRana cascadaeA frog of mountain meadows and ponds that has declined sharply in the Lassen region.
Pacific treefrogPseudacris regillaA tiny, loud frog of wet meadows.
Long-toed salamanderAmbystoma macrodactylumBreeds in ponds soon after snowmelt.
Rough-skinned newtTaricha granulosaA toxic newt found in ponds and lakes.
Western terrestrial garter snakeThamnophis elegansThe most common snake around lakes and meadows.
Sagebrush lizardSceloporus graciosusBasks on sunny rocks and logs.
Rubber boaCharina bottaeA small, gentle snake that burrows under logs.

Fish

Rainbow troutOncorhynchus mykissFound in park lakes and streams.
Brook troutSalvelinus fontinalisA non-native trout introduced to many high lakes.
Brown troutSalmo truttaA non-native trout introduced to some park waters.
Speckled daceRhinichthys osculusA small native minnow of streams.
Tui chubSiphateles bicolorA native minnow of lakes in the eastern part of the park.

Species totals are the park's certified NPSpecies checklist (occurrence: present).

Climate & When to Visit

Lassen's climate is shaped by elevation and Pacific winter storms. At the southern tip of the Cascades, the park rises high enough to squeeze tremendous snowfall from winter systems. Around Lake Helen, near 8,200 feet, annual snowfall averages about 600 to 700 inches, while the Kohm Yah-mah-nee Visitor Center at 6,867 feet averages about 430 inches. Much of the main park highway is buried under snow from roughly late fall to early summer.

Summers are dry, sunny, and usually mild, as high pressure blocks storms off the Pacific. The park reports average July highs near 88°F with lows around 50°F at its lower elevations, and much cooler conditions at the peak. Afternoon thunderstorms bring lightning to exposed summits, and dry summer forests are prone to wildfire; the 2021 Dixie Fire burned a large part of the park. Winters bring January highs near 40°F and lows around 21°F, with frost on about 164 days a year.

Spring
Still deep winter in the high country; snowmelt swells creeks while snow blocks the main road and most trails.
Summer
The best time to visit, with sunny, dry days; the highway and higher trails open as snow melts, often not until July, and wildflowers bloom through August.
Autumn
Crisp, clear days, golden aspens, and few crowds, until the first big storms bring snow in October or November.
Winter
Heavy snow closes the park highway; snowshoeing and skiing are popular near the Manzanita Lake and southwest entrances.

Weather hazards

Hydrothermal areas: Stay on boardwalks and trails, because thin crusts over boiling water and acidic mud can collapse.
Lightning: Leave Lassen Peak and other exposed summits if thunderstorms build in the afternoon.
Snow and avalanches: Snow can cover trails into July, and steep slopes can slide in winter and spring.
Altitude and sun: High elevation brings thin air and strong UV, so bring water and sun protection.
Wildfire and smoke: Check fire closures and air quality in late summer and early autumn.

Lassen Volcanic Questions

When is the best time to visit Lassen Volcanic National Park?

Mid-July through September is ideal, once snow clears from the park highway and trails. July and August bring the most wildflowers, and September offers quiet, clear days before winter storms return.

Is Lassen Peak still an active volcano?

Yes. Lassen Peak last erupted from 1914 to 1917, and the park's hydrothermal areas show that heat still rises from below. The U.S. Geological Survey monitors the Lassen Volcanic Center.

What are the four types of volcanoes in the park?

Lassen has all four major types: plug domes like Lassen Peak, shield volcanoes like Prospect Peak, cinder cones like Cinder Cone, and composite volcanoes represented by the eroded remains of Brokeoff Volcano.

How much snow does Lassen get?

A great deal. The area around Lake Helen averages about 600 to 700 inches of snow each year, and the park highway is often snowbound until June or later.

What is Bumpass Hell?

Bumpass Hell is the park's largest hydrothermal area, a basin of boiling springs, mud pots, and steaming vents reached by a trail from the park highway. Its hottest features reach about 198°F.

What wildlife might I see?

Mule deer, golden-mantled ground squirrels, and Steller's jays are common. Look for pikas in rock piles, black bears in meadows, and ospreys fishing at Manzanita Lake.

More parks in the Pacific West

← Lake Clark National Park & Preserve Mammoth Cave National Park →

Sources: www.nps.gov · en.wikipedia.org · en.wikipedia.org · www.nps.gov · irmaservices.nps.gov · Official NPS site