What counts as an aurora tour
A row is a single bookable product sold by a single operator from a single base, whose description promises time spent looking for the aurora. A husky ride that mentions the northern lights in passing is marked as a bundled product, with the aurora time stated separately from the total length. A glass-roof hotel night is a stay, not a tour, and is held in a separate row type.
Where each figure comes from
Price, group size, length and inclusions are read from the operator’s own page where one exists, and from its GetYourGuide, Viator or Guide to Iceland listing where it does not. Every row carries the date it was read. We do not estimate a price, convert an old one forward, or average across products to fill a gap: a missing value stays missing.
Retry, rebooking and refund rules are quoted from the operator’s terms, not paraphrased, because the difference between "we will take you again" and "we will take you again if we cancel" is the whole point of the column.
Ratings are a dated snapshot of what the marketplace showed on the day we read it. They are not our assessment, and they are never used to order a table.
The two columns that are ours
Dark hours per month, per base, are computed from standard astronomy formulas as the time the sun spends more than 12 degrees below the horizon. No licence is needed for that and no external data is used.
Clear-sky share per month, per base, comes from public cloud-cover climate normals published by national meteorological services. Before any clear-sky figure appears on the site, the source for each base and that source’s reuse terms will be named here. Where a source’s terms do not permit republication, the figure will be computed from open reanalysis data instead, and that will be said here too.
Expected cost per night that ends in a sighting is ours: the price divided by an estimated probability that one night under that operator’s policy produces a sighting. It is a model, not a measurement. Its formula and the width of its error will be printed here before it is published, and it will always be labelled as a derived figure.
What we will not claim
We do not forecast tonight’s aurora. We do not rank operators by anything other than the columns in the table. We do not list an operator higher because we are paid for its bookings, and the affiliate relationship is set out on the disclosure page.
How often it is re-checked
Core bases are re-checked monthly from September to March and every two months from April to August. The re-check date on a row is the date the row was read, not the date the page was built.
Corrections
Operators and readers can write to the address on the contact page. A corrected row keeps its history: we change the value and the date, and say what changed.
License
Row snapshots may be quoted with attribution to Northern Lights Index and a link to this page. All other rights reserved.