Conditions right now
Northern Norway: Kp 0.33 · 17 GW hemispheric power · Bz -2 nT · 410 km/s solar wind
The chance of seeing the northern lights in the next hour is worked out from the solar wind
(Bz and speed), with the Kp index in support. It can only be seen once the sky is dark and clear.
Readings come from NOAA, cloud forecasts from the Norwegian Meteorological Institute.
What decides whether the northern lights are visible tonight?
Three things have to come together: geomagnetic activity strong enough to push the auroral oval over you, a dark sky, and no clouds. This page reads the solar wind (Bz and speed) for the next hour, the Kp index for what is happening now, and the cloud forecast for your spot.
What is the Kp index?
Kp is a 0 to 9 scale of geomagnetic activity, averaged over three hours. In northern Norway, around Tromso and Lofoten, Kp 2 to 3 is already enough for aurora because the region sits under the auroral oval. Further south you need much higher values.
What does Bz mean?
Bz is the north-south direction of the magnetic field carried by the solar wind, measured in nT. When Bz turns negative (southward) it connects with the earth's magnetic field and lets energy in, which is the best short-term sign of aurora. The satellite measuring it sits upstream, so it warns 30 to 60 minutes ahead.
When is the aurora season in northern Norway?
From late August to mid April, when the nights are dark. Between late May and late July the midnight sun makes the aurora invisible even when the activity is high.
Does cloud cover stop the northern lights?
Yes. The aurora is far above the clouds, so an overcast sky hides it completely. This page shows the cloud forecast hour by hour for 17 places in northern Norway, Sweden and Finland, or for your own position on a phone.
Where do the numbers come from?
Geomagnetic and solar wind data from NOAA Space Weather Prediction Center, cloud forecasts from the Norwegian Meteorological Institute (met.no), and the aurora map from UiT, The Arctic University of Norway.
Why is a camper van so good for chasing the aurora?
Because the weather decides, and the weather moves. A forecast is never certain and the sky can be overcast in one fjord and clear in the next, so the trick is to drive to where the sky is clear instead of hoping it clears above you. A camper also takes you away from town and its light pollution, which is what hides a weak aurora. You park with the back window facing north, keep the heater on and the tea hot, and wait in the warm rather than standing outside for hours. When the sky does light up you are already there, the tripod is set up outside, and you can stay as long as the show lasts instead of following a tour schedule. If it is quiet you sleep on the spot, take turns watching the sky every ten or fifteen minutes, and catch up on sleep during the day. Arctic Campers rent winter ready camper vans in northern Norway for exactly that.
How to chase the Northern Lights — the full guide
