5 guides
Forecasts and data
How to read the Kp index, solar wind data and cloud forecasts – and use them to decide what to do tonight.
The Kp index explained: what the number means for the aurora
Kp is a global 0–9 measure of how disturbed Earth's magnetic field is. How to read it, which Kp is enough where you are in Norway, and when not to trust it blindly.
How to read an aurora forecast, from 27 days to the next hour
Aurora forecasts exist for the next hour and the next month, but their accuracy differs hugely. How to use each one, and an evening routine that actually works.
Clouds and clear skies: the real key to seeing the aurora
The aurora is above the clouds, so the cloud forecast matters at least as much as Kp. How to read cloud layers on Yr, choose between coast and inland, and dodge moonlight and city glow.
Aurora apps and data sources: where the numbers come from
Most aurora apps rely on a handful of open sources: NOAA for space weather, MET Norway and Yr for clouds, and Norwegian observatories for live measurements. How to use them, and how to tell a good app from a bad one.
How Nordlys i natt? works: yes, maybe or no
Behind the JA, KANSKJE or NEI answer are three open data sources and a few simple, open rules. How the verdict is made, where it can go wrong, and what happens to your location.