We combine satellite-measured darkness data, real-time weather analytics, and community-verified conditions to rate every aurora viewing location on a 0-100 scale.
Light pollution is the #1 enemy of aurora visibility
The Bortle Dark-Sky Scale (1-9) measures how dark the night sky is at a given location. A Class 1 site is a truly pristine dark sky where the zodiacal light and gegenschein are visible. A Class 9 site is a brightly-lit inner city where only the Moon, planets, and a few stars can be seen.
We determine each location's Bortle class using VIIRS satellite night-time radiance data from NASA's Suomi NPP satellite. This gives us objective, globally consistent measurements of artificial light at night — updated annually.
Bar width = relative sky darkness. Points = bonus added to Aurora Score.
Even the darkest location is useless under clouds
Aurora borealis happens 100+ km above Earth's surface, but clouds at 1-10 km altitude can block the view entirely. We analyze historical cloud cover data to identify locations with the best odds of clear skies during peak aurora season (September-March).
The Finnish Meteorological Institute (Ilmatieteen laitos) provides decades of climate records. We use their historical cloud cover statistics as our baseline for regional cloud patterns.
For each hotel location, we fetch 10 years of monthly cloud cover averages via the Open-Meteo Historical Weather API. This gives us precise, coordinate-level data rather than regional estimates.
We focus on February cloud cover as the key metric — the peak aurora season month with the longest dark hours. Locations averaging below 40% cloud cover earn a +10 point bonus to their Aurora Score.
Cloud Cover Bonus
< 40% = +10 pts
Four components, one definitive rating
Maximum Possible Score: 100 Points
Base Score
Every location starts at 50 points — within the Aurora Oval zone.
Darkness Bonus +0 to +40
Based on VIIRS-measured Bortle class. Darker = higher bonus.
Clear Sky Bonus +10
Awarded when February average cloud cover is below 40%.
North-Facing Bonus +10
Accommodation with unobstructed northern horizon for aurora viewing.
Pristine dark sky, clear conditions, optimal orientation. Best-in-class.
Good dark skies with some compromises. Great for most aurora hunters.
Significant light pollution or cloud cover. Aurora may only be visible during strong storms.
Data-driven, community-verified
Satellite data and weather APIs give us a strong foundation, but nothing replaces boots on the ground. Every listing on AuroraRadar goes through human verification before being published.
We partner directly with Lapland hotels and wilderness lodges. Each property confirms their coordinates, north-facing facilities, and aurora alert services.
Community-submitted aurora sightings and photographs help us validate that specific locations deliver on their dark-sky promise. Real observations confirm our satellite data.
Aurora Scores are recalculated monthly. Weather data refreshes automatically, and Bortle classes update when new VIIRS data is released. No stale ratings.
Drag the slider to see how the night sky changes from a pristine Class 1 dark site to an inner-city Class 9 location. Watch the stars disappear and light pollution take over.
Class 3
Rural Sky
Score Bonus
+20
Browse our curated collection of aurora-optimized accommodations, each scored using the methodology you just learned about.