How dark is the sky in Boulder, CO?

Boulder's sky measures suburban here. Light dome dominates much of the sky. Only the brightest stars and planets stand out clearly. Only 85.2% of the 3,206 cities measured here read darker than Boulder.

Worth remembering: this is satellite radiance, not a ground observation. A true Bortle rating needs a human eye at night, this is the closest large-scale substitute.

The nearest darker sky to Boulder

Louisville, CO, about 7 miles away as the crow flies, measures in the rural band, one step darker than Boulder. Actual driving distance will run longer than that straight-line figure.

Louisville, CO is itself still a measured city, not a designated dark-sky park, this only compares against the 3,206 places this dataset covers.

Boulder against the rest of the dataset

Boulder, CO counts roughly 106,803 residents, among the 3,206 US cities this site tracks. Among all 3,206 cities here, Boulder ranks 2,716 from darkest to brightest, 1 being the darkest measured.