How dark is the sky in Arizona?
Sky darkness for 64 towns and parks in Arizona, worked out from NASA satellite images of light at night (2025). 40 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Kaibab National Forest (21.90, Bortle 2), the brightest Phoenix (17.18, 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 Arizona
- Kaibab National ForestBortle 221.90
- Apache-Sitgreaves National ForestsBortle 321.86
- Vermilion Cliffs National MonumentBortle 321.85
- Navajo National MonumentBortle 321.84
- Petrified Forest National ParkBortle 321.84
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 Arizona
All 64 places in Arizona
Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Agua Fria National Monument4Apache-Sitgreaves National Forests3Avondale8Boyce Thompson Arboretum4Buckeye7Camp Verde5Canyon de Chelly National Monument4Casa Grande7Casas Adobes7Chandler8Chiricahua National Monument3Coconino National Forest4Coronado National Forest4Crook National Forest4Flagstaff6Flagstaff Area National Monuments3Fountain Hills7Gila Box Riparian National Conservation Area4Gilbert8Glen Canyon National Recreation Area4Glendale8Grand Canyon National Park4Grand Canyon-Parashant National Monument4Homolovi State Park4Ironwood Forest National Monument4Jerome State Historic Park4Kaibab Band of Paiute Indians3Kaibab National Forest2Kartchner Caverns State Park4Lake Havasu City6Las Cienegas National Conservation Area4Mesa8Montezuma Castle National Monument4Navajo National Monument3Oracle State Park4Organ Pipe Cactus National Monument4Peoria8Petrified Forest National Park3Phoenix8Picacho Peak State Park4Pipe Spring National Monument4Prescott National Forest5Saguaro National Park4San Pedro Riparian National Conservation Area4San Tan Valley6Scottsdale8Sedona5Slide Rock State Park4Sonoran Desert National Monument4Sunset Crater Volcano National Monument4Surprise8Tempe8Tempe Junction8Tonto National Forest4Tonto National Monument4Tonto Natural Bridge State Park4Tucson8Tumacácori National Historical Park4Tuzigoot National Monument4Vermilion Cliffs National Monument3Village of Oak Creek5Walnut Canyon National Monument4Wupatki National Monument3Yuma7