AuroraDo clouds block the northern lights?
Yes. The northern lights happen about 100 km up or higher, and almost all weather happens below 12 km, so a thick layer of cloud hides the aurora completely, however strong it is. Thin or broken cloud only dims it, and gaps can open quickly.
Cloud is also the most common reason people miss the aurora in the far north. Under the auroral oval in northern Norway, Sweden and Finland, there is some aurora on most dark nights. Whether you see it depends mostly on the sky above you.
How often is it clear enough?
We went through ten winters of hourly weather reports (METAR) from the airport nearest each destination, September to March, 2016–2026. A night counts as usable when it had at least two dark hours free of broken or overcast low cloud.
| Destination | Nights with 2+ dark hours free of low cloud | Best month | Cloudiest month | Airport |
|---|---|---|---|---|
| Alta | 73% | December (86%) | September (52%) | ENAT |
| Abisko | 62% | January (72%) | September (44%) | ESNQ |
| Kiruna | 62% | January (72%) | September (44%) | ESNQ |
| Kirkenes | 60% | January (74%) | September (50%) | ENKR |
| Yellowknife | 58% | March (74%) | November (39%) | CYZF |
| Saariselkä | 58% | January (69%) | October (45%) | EFIV |
| Tromsø | 58% | December (70%) | September (45%) | ENTC |
| Levi | 58% | March (74%) | October (46%) | EFKT |
| Lofoten | 56% | December (66%) | September (44%) | ENEV |
| Rovaniemi | 52% | March (65%) | October (42%) | EFRO |
| Fairbanks | 48% | January (62%) | September (30%) | PAFA |
| Iceland | 48% | December (58%) | October (41%) | BIKF |
Two things stand out:
- Inland beats coastal. Alta, in a dry fjord valley, and Kiruna and Abisko, in the rain shadow of the mountains, had a usable sky more often than coastal Tromsø, Lofoten or Reykjavík.
- No place is cloud-free. Even the clearest destination lost about one night in four to low cloud, and the cloudiest lost about half.
These figures count low cloud only. An airport report of "no cloud below 1,500 m" counts as clear, so thin high cloud that dims the aurora can still be there. An airport can also be cloudier or clearer than the place you stand. All sources and definitions are on our methodology page.
Can you see the northern lights through clouds?
Not through thick cloud. You can see them:
- through thin, high cloud, as a dimmer and blurred glow;
- in gaps in broken cloud, often briefly;
- beyond the edge of a cloud bank, low on the northern horizon.
A camera picks up aurora through thin cloud that your eyes can't. If your phone shows green and you see grey, that is usually why.
Does a high Kp mean clear skies?
No. Kp measures activity in the Earth's magnetic field and says nothing about clouds. We checked this directly at 11 northern Scandinavian airports in the 2025–26 winter (2,213 airport-nights):
- on all nights, low cloud covered the sky all night 40% of the time;
- on nights a Kp-style forecast called good (Kp 4 or more, or a high NOAA storm chance), it was 41%: no better;
- on nights our forecast rated Good or Excellent, it was 7%, because the forecast looks at clouds as well as activity.
More on this in why the Kp index isn't enough.
How to deal with clouds on an aurora trip
- Look at a cloud forecast for low, medium and high cloud separately. Low cloud is the deal-breaker. Thin high cloud only dims the aurora.
- Be ready to drive. On many nights, the coast is cloudy while the inland valleys are clear, or the other way round. An hour on the road can make the night.
- Book more than one night. Clouds come and go in spells of a few days. Several nights give you several chances.
- Check again in the evening. Cloud forecasts improve as the night gets closer.
Which destinations are least cloudy?
In our data, Alta had the most usable nights, followed by Kiruna and Abisko, then Kirkenes, Yellowknife and Saariselkä. Reykjavík and Fairbanks had the fewest. Each destination page shows the month-by-month figures, for example Alta, Abisko and Tromsø.
What our forecast does with clouds
Aurora's Tonight number combines solar wind, the Kp index and its forecast, darkness, the moon and a cloud forecast for low, medium and high cloud at your place. That is why it can rate a strong Kp night as Low when thick cloud is coming, and a quiet night as Good when the sky will be clear. A forecast, not a guarantee.
