AuroraWhen is the best time to see the northern lights?
From late September to late March, almost anywhere under the auroral oval. Inside that window, three things decide your odds, in this order: how dark the nights are, how often the sky is clear, and whether the moon is up. Solar activity matters too, but it can't be planned more than a few days ahead.
Month by month, by destination
The table shows, for each destination, the month when the all-sky camera saw aurora most often (only near our four cameras) and the months with the most and fewest nights free of low cloud at the nearest airport over ten winters (2016–26). Such a night has at least two dark hours without broken or overcast cloud below about 1,500 m; airport reports often can't see higher cloud.
| Destination | Aurora seen most often (camera) | Month freest of low cloud (airport) | Cloudiest month |
|---|---|---|---|
| Tromsø | January (47%) | December (70%) | September (45%) |
| Abisko | November (71%) | January (72%) | September (44%) |
| Kiruna | January (54%) | January (72%) | September (44%) |
| Alta | no camera | December (86%) | September (52%) |
| Lofoten | no camera | December (66%) | September (44%) |
| Kirkenes | no camera | January (74%) | September (50%) |
| Rovaniemi | no camera | March (65%) | October (42%) |
| Levi | no camera | March (74%) | October (46%) |
| Saariselkä | no camera | January (69%) | October (45%) |
| Iceland | no camera | December (58%) | October (41%) |
| Fairbanks | no camera | January (62%) | September (30%) |
| Yellowknife | no camera | March (74%) | November (39%) |
Two things stand out. First, the clearest month differs a lot between places that are only a few hundred kilometres apart, so check your own destination rather than a general rule. Second, September to November is the least clear stretch almost everywhere in the table, and the clearest month falls in midwinter or late winter.
Darkness sets the outer limits
Aurora needs a dark sky: the sun at least 12° below the horizon. At 69°N that gives about six dark hours in mid-September, around sixteen in mid-December and eight in mid-March. Each destination page lists the dark hours for every month.
Long nights help in a second way: with sixteen dark hours, a night is more likely to have a clear window somewhere in it. That is part of why December and January score well in the airport column at many places, even where single hours are often cloudy. September and March have short nights, so a clear spell has to come at the right time.
The moon decides which week
A bright moon hides faint aurora, while strong displays still show through. The week around new moon gives the darkest skies. Use the northern lights calendar to see how many dark hours have no moonlight on every night of the season at your destination.
How many nights should you plan?
Even in the best month, clouds and quiet activity rule out many nights. Three to five nights in one place give you far better odds than one night in the "best" place. When you are there, a forecast that combines activity, cloud layers, darkness and the moon tells you which of your nights to stay up for.
Where the numbers come from
Camera nights come from the UEC Tromsø AI classification of all-sky cameras in Tromsø, Abisko and Kiruna. Low-cloud nights come from hourly airport weather reports (METAR) in the Iowa Environmental Mesonet archive. Darkness is computed. Definitions and limits are on How we know.
