How dark is the sky in California?
Sky darkness for 222 towns and parks in California, worked out from NASA satellite images of light at night (2025). 84 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Modoc National Forest (21.89, Bortle 3), the brightest Los Angeles (16.94, Bortle 8).
19
Bortle class, 1 pristine to 9 city center
park or dark-sky place
city
Numbers like 21.95 or 16.97 are the brightness of the sky overhead on a clear, moonless night, in mag/arcsec². The scale runs backwards: a lower number means a brighter sky, from about 22 for a natural sky to about 17 in a city center.
How the readings are made
Darkest skies in California
- Modoc National ForestBortle 321.89
- Sáttítla Highlands National MonumentBortle 321.89
- Lava Beds National MonumentBortle 321.87
- Humboldt Redwoods State ParkBortle 321.86
- Klamath National ForestBortle 321.86
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.
Brightest city skies in California
All 222 places in California
Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Ahjumawi Lava Springs State Park3Anaheim8Andrew Molera State Park4Antioch7Anza-Borrego Desert State Park4Apple Valley7Arden-Arcade8Armstrong Redwoods State Natural Reserve4Austin Creek State Recreation Area4Año Nuevo State Park4Bakersfield8Berkeley8Berryessa Snow Mountain National Monument4Borrego Springs4Bothe-Napa Valley State Park4Brentwood7Burbank8Butano State Park4Calaveras Big Trees State Park4Camarillo7Carlsbad7Carmel River State Beach4Carrizo Plain National Monument4Castle Mountains National Monument4Cathedral City8Cayucos State Beach4Cesar E. Chavez National Monument4Channel Islands National Park4Chico7Chuckwalla National Monument4Chula Vista8Chumash Painted Cave State Historic Park4Cleveland National Forest4Clovis8Compton8Concord8Corona8Costa Mesa8Cuyamaca Rancho State Park4D. L. Bliss State Park4Daly City8Davis7Death Valley National Park4Delano7Devils Postpile National Monument4Donner Memorial State Park4Downey8East Los Angeles8Eastvale8Ed Z'berg Sugar Pine Point State Park4El Cajon8El Capitán State Beach4El Monte8Eldorado National Forest4Elk Grove8Emerald Bay State Park4Encinitas7Escondido8Fairfield7Florence-Graham8Folsom8Fontana8Fort Ord National Monument5Fort Ross State Historic Park4Fort Tejon4Fremont8Fresno8Fullerton8Garden Grove8Garrapata State Park4Giant Sequoia National Monument4Gilroy7Glendale8Glendora8Grizzly Creek Redwoods State Park3Grover Hot Springs State Park4Hanford7Hayward8Hearst Castle4Hemet8Hendy Woods State Park4Hesperia7Humboldt Redwoods State Park3Huntington Beach8Indio8Inglewood8Irvine8Jedediah Smith Redwoods State Park4Joshua Tree National Park4Julia Pfeiffer Burns State Park4Kings Canyon National Park4Klamath National Forest3Laguna Niguel7Lake Elsinore7Lake Tahoe Basin Management Unit4Lancaster8Lassen National Forest3Lassen Volcanic National Park3Lava Beds National Monument3Livermore7Lodi8Long Beach8Los Angeles8Los Padres National Forest4Madera7Manteca8McArthur-Burney Falls Memorial State Park4Mendocino Headlands State Park4Mendocino National Forest3Menifee7Merced7Milpitas8Mission Viejo8Modesto8Modoc National Forest3Mojave National Preserve4Mojave Trails National Monument4Montaña de Oro State Park4Monterey Park8Moreno Valley8Muir Woods National Monument5Murrieta8Napa7Navarro River Redwoods State Park3Norwalk8Novato6Oakland8Oceanside7Ontario8Orange8Oxnard8Palm Desert8Palmdale8Palo Alto8Pasadena8Perris8Petaluma6Pfeiffer Big Sur State Park4Pinnacles National Park4Pleasanton7Plumas National Forest4Point Lobos State Natural Reserve4Point Reyes National Seashore4Pomona8Porterville7Poway7Rancho Cucamonga8Red Rock Canyon State Park4Redding7Redlands8Redwood City8Redwood National Park4Rialto8Richmond8Riverside8Robert Louis Stevenson State Park4Roseville8Sacramento8Salinas7Salt Point State Park4Samuel P. Taylor State Park4San Bernardino8San Bernardino National Forest4San Clemente7San Diego8San Francisco8San Jose8San Leandro8San Mateo8San Rafael7San Ramon7Sand to Snow National Monument5Santa Ana8Santa Barbara7Santa Clara8Santa Clarita8Santa Cruz7Santa Maria7Santa Monica8Santa Rosa7Santa Rosa and San Jacinto Mountains National Monument5Sequoia National Forest4Sequoia National Park4Shasta-Trinity National Forest4Sierra National Forest4Simi Valley8Six Rivers National Forest3Smith River National Recreation Area3Sonoma Coast State Park4South Yuba River State Park4Stanislaus National Forest4Stockton8Sunnyvale8Sáttítla Highlands National Monument3Tahoe National Forest4Temecula7Thousand Oaks7Tomales Bay State Park4Torrance8Tracy8Tulare8Tule Lake National Monument4Turlock8Vacaville7Valencia8Vallejo7Ventura7Victorville7Visalia8Vista8Walnut Creek8Watsonville7Weaverville Joss House State Historic Park4West Covina8Whiskeytown-Shasta-Trinity National Recreation Area4Whittier8Woodland7World War II Valor in the Pacific National Monument4Yorba Linda8Yosemite National Park4Yuba City7Yucaipa7