Live · 69.6°N · Tromsø
Aurora forecast for Tromsø
Three things must line up: activity, a gap in the cloud, real darkness.
69°39′N 018°57′E · TROMSØ
Tonight in Tromsø
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Three things must line up
Activity · Kp
Cloud while dark
Dark hours
Overhead now
Sources: Kp forecast and OVATION aurora model, NOAA Space Weather Prediction Center (public domain). Cloud: MET Norway Locationforecast, CC BY 4.0. Darkness: the NOAA solar equations, computed at sea level for Tromsø (69.65°N 18.96°E). Times are Tromsø time.
How to read it
Three things have to line up: activity in the sky, real darkness and a gap in the cloud. Miss any one and there's nothing to see.
Kp: how busy the sky is
Kp is a planet-wide index of geomagnetic activity, from 0 (quiet) to 9 (extreme), given in 3-hour blocks. NOAA calls Kp 5 and above a geomagnetic storm, from G1 at Kp 5 to G5 at Kp 9.
Why Tromsø needs less
Tromsø lies under the auroral oval, the ring around the magnetic pole where aurora is most frequent. So a modest Kp of 2 or 3 can be enough to put the aurora overhead here, while places much further south need a geomagnetic storm.
The nowcast
NOAA's OVATION model turns the solar wind measured on its way to Earth into a map of the chance of aurora overhead, roughly 30 to 90 minutes ahead. We read the grid cell nearest Tromsø. It knows nothing about daylight or cloud, so read it next to the other two.
Cloud is the usual spoiler
A busy sky behind solid cloud shows you nothing. Cloud also changes over a few miles: one fjord overcast, the next one clear. That's why, on our winter voyages, we move the boat on the cloud forecast rather than wait in one place.
How we make the call
The label at the top comes from a simple rule over tonight's dark hours, the same for every night:
- Good chanceKp 3 or more while it's dark, and cloud at 40% or less.
- PossibleKp 2 or more with cloud up to 70%, or Kp 4 or more with cloud up to 85%.
- UnlikelyAnything below that: too little activity, too much cloud, or both.
- Too brightThe sun stays above −6° for the next 24 hours, so there are no dark hours.
- No callThe Kp or the cloud forecast is missing, and we don't guess.
Kp is the highest 3-hour value, estimated or forecast, that overlaps the dark hours. Cloud is the average of MET Norway's hourly forecast over the same hours. If it's already dark with less than an hour to go, we look at the next night. A rule of thumb, never a promise.
The bright months
Around midsummer Tromsø never gets dark enough for aurora.
Nights too bright for aurora in Tromsø
28 Apr–13 Aug 2026
2026 · too bright for aurora
29 Apr–13 Aug 2027
2027 · too bright for aurora
Computed at sea level for Tromsø (69.65°N) with the NOAA solar equations.
More
The aurora doesn't switch off in summer; it just can't be seen. You need the sun more than about 6° below the horizon (the end of civil twilight), and around midsummer Tromsø never gets that dark.
Each date is the evening the night begins. Computed at sea level for Tromsø (69.65°N) with the NOAA solar equations: on those nights the sun's centre never goes more than 6° below the horizon. Outside them every night has some dark hours, and on 21 December 2026 the sun stays below −6° for 19.6 hours.
Tips for watching the sky
Works anywhere under the auroral oval: a beach, a hillside or a deck.
Let your eyes adjust
Give your eyes about 20 minutes away from screens and white light. Use a red head torch and turn your phone's brightness right down.
Look north, then up
With a quiet sky the aurora often sits low in the north from Tromsø; when activity picks up it can climb overhead and spread across the sky. Check the north first, then straight up.
Late evening to the small hours
Around Tromsø the aurora is often most active between about 20:00 and 02:00, but it can come and go at any point in the dark hours. Step out every half hour rather than waiting for one big moment.
Your phone sees more
A faint aurora can look like a pale grey cloud to the eye; a phone in night mode often shows the green. Brace it against something solid while it exposes.
Shooting from a deck
A boat moves even at anchor, and a tripod moves with it. Keep exposures short (1 to 4 seconds), raise the ISO, open the lens as wide as it goes and take plenty of frames.
Dress for standing still
Watching the sky means standing still outside for a long time. Layers, a hat, mittens over thin gloves and warm boots.
Aurora from the water
Our northern lights & whales season sails from Tromsø in winter 2027–28 (dates provisional): short voyages into the fjords and islands of Northern Norway, moving the boat on the cloud forecast.
Planning to sail up here?
Cap II's 2027 season sails from Tromsø: Svalbard in June–July, northern lights and whales in winter 2027–28. All dates are provisional.