How we check

How we find the properties

We searched Google Maps for glass igloos, glass cabins, aurora domes and snow hotels in 38 areas across the aurora zone, then pinned the location of each place from its own coordinates. That gave 433 places to stay. We dropped holiday rentals, tour companies and places with no glass room, which left 76 in 25 areas. We publish an area once its stays are fully checked: 34 so far.

How we check the rooms

We read each property's own website, page by page, and write down what it says about the glass room: its name, its size, how many it sleeps, and five facts: heated or defrosting glass, an aurora alarm, a private sauna, a private hot tub and an own bathroom.

Every quote on the site is copied word for word from the property's website, with a link to the page. Our build stops if a quote can't be found in what we read, so we can't publish a quote that isn't there.

An aurora alarm counts only when it is in the room. If the property only recommends a phone app, we say so. When a website doesn't mention a fact, we write "not stated". That happens 79 times across the 34 stays. It may still be there: ask before you book.

The best nights calendar

Each stay's page rates every night of the next six months. Three things go into it.

Dark hours. The sun has to be 12° or more below the horizon. We work this out for the property's own location, night by night.

Moonlight. A bright moon washes out faint aurora. We count the dark hours when the moon is below the horizon or less than a quarter lit. Moon positions and phases are exact.

Clear sky. Nobody can forecast cloud months ahead, so we use how often that time of year has been clear. A clear hour has 2 oktas of cloud or less in hourly weather-station reports, over ±10 days around each date. Stations used: Rovaniemi: Rovaniemi railway station (Finnish Meteorological Institute, CC BY 4.0, seasons 2015 to 2025); Saariselkä, Inari: Ivalo airport (Finnish Meteorological Institute, CC BY 4.0, seasons 2015 to 2025); Levi: Kittilä airport (Finnish Meteorological Institute, CC BY 4.0, seasons 2015 to 2025); South Iceland: Reykjavík weather station (NOAA Integrated Surface Database (Icelandic Met Office reports), public domain, seasons 2014 to 2026). Each stay's page gives its distance to the station. The Iceland stays are 80 to 110 km from Reykjavík, the nearest station with usable cloud records.

A night's rating is its moonless dark hours times its typical clear share. The "best 4-night stays" are the four-night runs with the highest total.

We tested satellite and weather-model cloud data against these stations before choosing them. In Reykjavík in December, the satellite data said 42% of dark hours were clear; the station recorded 19%. So we use station records.

The next 7 nights

The live strip on each stay's page shows cloud cover for every dark hour from the MET Norway forecast (hourly for about 2 days, then every 6 hours; CC BY 4.0), and the aurora activity forecast from the NOAA Space Weather Prediction Center.

Aurora activity is shown as the Kp index. Around Rovaniemi and Iceland, Kp 2 to 3 is often enough for an aurora overhead on a clear night. Higher numbers push it further south and make it brighter. It is refreshed every 30 minutes.

How dark the sky is

We measure artificial light around each property from NASA's VIIRS night lights satellite images (2016 composite, public domain), weighting nearby lights more than distant ones. The result is one of four levels, from very dark sky to bright town glow, plus the distance and direction of the nearest bright lights.

What we can't tell you

Whether the aurora will appear on your dates. Aurora activity can only be forecast about three days ahead and cloud about a week ahead. Anyone selling a six-month aurora forecast is guessing. Our calendar shows which nights give you the best odds, not a promise.

How we earn money

Booking buttons go through Stay22 to Booking.com, Expedia or Hotels.com. If you book, we may earn a commission at no extra cost to you. Properties cannot pay to be listed or to change what we say. Affiliate disclosure.