Weather · tonight, Sunday 1 November
Kp up to 4.7 tonight (NOAA scale G1, a geomagnetic storm). A good chance in Abisko, Kiruna, Jokkmokk, Luleå and Östersund.
in the mountains of Lapland, 200 km north of the Arctic Circle, with a rain shadow that keeps its sky clearer than most
Kp 4.7 forecast, well above the Kp 1 that usually brings the aurora here. Clear for about 3 hours, clearest around 23:00.
in Lapland, Sweden’s northernmost town, 145 km north of the Arctic Circle
Dark and clear now: worth a look outside
Kp 4.7 forecast, well above the Kp 2 that usually brings the aurora here. Clear for about 9 hours, clearest around 22:00.
on the Arctic Circle, the Sami market town in the forests of Lapland
Kp 4.7 forecast, well above the Kp 2 that usually brings the aurora here. Clear for about 9 hours, clearest around 23:00.
on the coast at the top of the Gulf of Bothnia
Kp 4.7 forecast, well above the Kp 3 that usually brings the aurora here. Clear for about 9 hours, clearest around 22:00.
in Jämtland, by Lake Storsjön in the middle of the country
Kp 4.7 forecast, enough here (Kp 4 or more). Clear for about 6 hours, clearest around 22:00.
on the east coast, where the aurora shows only in strong storms and low in the north
Kp 4.7 at most, and the aurora usually needs Kp 6 or more here. Cloud covers the sky all night.
Three things have to line up. The sun has to be active enough: NOAA's Kp forecast says how disturbed Earth's magnetic field will be tonight, and each place needs a certain Kp before the aurora reaches it, from Kp 1 in Abisko to Kp 6 in Stockholm. The sky has to be clear: SMHI's forecast gives the cloud cover hour by hour, and a clear hour is one with at most three eighths of the sky covered. And it has to be dark: from about an hour after sunset to an hour before sunrise.
A good chance means enough Kp and at least three clear hours; some chance means one of them is short. "Aurora model now" is NOAA's OVATION model, the probability of aurora overhead at the place for the next hour or so. All of it is a forecast: storms arrive early or late, and clouds move.
From September to March. The aurora is there all year, but from April to August the nights in the north are too light to see it. The darkest months, November to January, give the most hours to watch; September, October, February and March often have clearer skies.
Swedish Lapland. Abisko and Kiruna sit under the auroral oval, so the lights show there even on quiet nights, and Abisko’s rain shadow keeps its sky clearer than most places. Further south, from Östersund to Stockholm, it takes a geomagnetic storm.
Kp measures how disturbed Earth’s magnetic field is, from 0 (calm) to 9 (an extreme storm), in three-hour periods. The higher it is, the further south the aurora reaches. Kp 5 is a minor storm (NOAA scale G1); at Kp 6 (G2) it can be seen low over the northern horizon from Stockholm.
Usually between 21:00 and 02:00, when the sky is fully dark, but a storm can light up any dark hour. Give it a clear spell, look north and check again every half hour: the lights come and go.
Sometimes, a few nights a year, when NOAA forecasts a storm of G2 or more and the sky is clear. Get out of the city lights, face north and look low over the horizon. A phone camera on night mode often catches colour the eye cannot.