Northern lights tonight

It is the chance that a northern lights cruise from Reykjavík would count tonight as a sighting: a show good enough that Elding doesn’t hand out retry tickets. Faint, camera-only displays count as no.

• The model was fitted on operated Elding cruises (). Cancelled nights are left out, because nobody saw what the sky did. On those nights, two things explained success: the real Kp during the cruise and the real cloud over Faxaflói.
• Tonight’s real values aren’t known yet, so the page uses NOAA’s Kp forecast, the latest Kp NOAA has measured, and ECMWF’s cloud forecast for the bay.
• NOAA’s Kp forecasts are rough: they correlate only about 0.35 with what happens. The most recent measured Kp is a much better guide, and the closer it is to the cruise, the more it counts. These weights were fitted on NOAA’s archived forecasts from 2022 onwards.
• The page averages over the likely range of Kp and over a cloud-forecast error of ± points, so it rarely says 0% or 100%.

Tested on the 38 cruises since 1 September 2026, which the model never saw, the afternoon version of the number scored an AUC of 0.91. It tends to run a few points optimistic on average.