Kp guide
Kp Index for Northern Lights Forecasts
Kp is a global geomagnetic index. It helps describe storm strength, but it should be read together with local sky conditions and aurora oval position.
What Kp measures
Kp summarizes geomagnetic disturbance on a planetary scale. A higher number usually means the aurora oval can push farther south, which improves the chance for mid-latitude viewers.
For a city-level forecast, Kp is one signal among several. A strong Kp value with heavy clouds can still be a bad viewing night.
How to use Kp for city decisions
High-latitude locations can see aurora at lower Kp values. Cities farther south often need Kp 5 or higher, plus darkness and a clear northern horizon.
Quick answers
What Kp do I need to see aurora?
It depends on latitude. Northern cities can work at lower Kp; mid-latitude cities often need Kp 5 or stronger.
Can Kp be high while my city score is low?
Yes. Clouds, twilight, light pollution, and aurora oval position can all lower the local viewing chance.