Northern Lights in Lapland

The three things that have to line up

The Northern Lights, or aurora borealis, are the most visible form of space weather: the effects of the solar wind and solar flares in the space around the Earth and in the upper atmosphere. They glow far above the weather, typically 80 to 500 km up, and you need three conditions at once to see them.

Cloud has no bearing on whether an aurora happens, only on whether you see it. Most displays come around midnight. The Finnish Meteorological Institute (FMI) gives 9 pm to 1 am local time as the strongest window; Visit Finland says 9 pm to 2 am.

The best places to see the Northern Lights

Start with latitude. FMI explains that the Northern Lights form an oval band around the Earth’s geomagnetic poles, and that about 2,500 km from those poles the chance of seeing them is almost 100%. Finland sits on the southern rim of that oval, so the further north you go, the more often the sky shows them. In FMI’s words, the chance is best in the northernmost part of the country, in Lapland. We plan aurora trips in Finnish Lapland for that reason, and it is where we do our own checking.

Inside Lapland, north still beats south. Kilpisjärvi is in the top band. Levi, Ylläs and Saariselkä are in the middle one. Rovaniemi lies further south, between Oulu and those resorts, and FMI’s aurora pages give it no figure of its own. Base yourself there and you will want more evenings out to make up the difference. Wherever you stay, the spot matters as much as the town. FMI advises open, dark ground away from settlements, and says an open view to the northern horizon is essential.

Outside Finland, FMI names the latitudes where auroras can typically be seen: northern Fennoscandia, Svalbard, Iceland, northern Canada, Alaska and Siberia. Of those, we compare two with Finnish Lapland. The Norwegian coast around Tromsø is in the sections below and in Finland or Norway for the Northern Lights. Swedish Lapland, with Abisko and Kiruna, is in Finnish or Swedish Lapland. Iceland is on FMI’s list too. This site does not cover it and we have not checked it.

How many nights give you a fair chance

Start from FMI’s figures in the table above, and look at what they count: only the dark, cloud-free nights. That makes them a ceiling. On a real trip your chance drops with every cloudy night you get, and when you book there is no knowing how many that will be. We looked for an official count of clear winter nights in Rovaniemi and found none, so you will not find a percentage here.

The tourist boards count differently. Visit Finland says the lights appear on roughly 200 nights a year in northern Finland, and Visit Rovaniemi says around 150 nights a year in Finnish Lapland when conditions are favourable. Neither figure is the number of nights you will see them from one place.

Every dark evening you keep free gives a clear sky and solar activity one more chance to coincide. So when we plan an aurora trip we count the evenings first and choose the place second.

Our rule is at least four nights. The arrival evening often goes on travel and unpacking, so four nights leaves three full evenings, and three nights leaves two, both of which one cloudy spell can take. The rule comes from planning judgement rather than any statistic. Four nights can still bring nothing, and a single night can bring a strong display.

• Leave your evenings open. Don’t book a dinner or an activity for every one of them.
• If you book a guided aurora trip, put it early in your stay, so a clouded-out night is not your last.
• Dress for standing still. FMI notes that the dark, cloudless nights you want are practically always cold in Finland.

Northern Lights inland or on the coast

The main alternative to inland Finnish Lapland is the Arctic Ocean coast of northern Norway, around Tromsø. Rovaniemi sits on the Arctic Circle; Visit Tromsø puts Tromsø about 350 km north of it, and FMI says the lights can be seen on that coast almost every night. The coast is also milder: Visit Tromsø gives an average winter temperature of about −4 °C, while at Rovaniemi airport the January average is −10.3 °C (FMI, 1991 to 2020).

Cloud gets in the way on both sides of the border. One operator listed by Visit Tromsø says its tours follow no fixed route: it uses the live weather to search for clearer skies, and may drive more than 200 km or cross into Finland. Which side is clear more often is an open question, as far as we can tell; we found no official comparison of the coast and inland.

On the coast, then, you get milder nights and a more northerly position, and sometimes a long drive on a chase night. Inland Finland is colder. In Rovaniemi, Visit Rovaniemi lists viewing places a short walk from the city centre, though darker ground further out shows more.

Finland or Norway for the Northern Lights sets out the whole comparison, including getting there from the UK, and Tromsø or Rovaniemi does the same for the two towns. Weighing a ship on the Norwegian coast against a week on land is a separate choice, covered in a Northern Lights cruise or Lapland.

When the Northern Lights season runs

The season runs from late August to early April, the months when the nights are dark enough. Visit Rovaniemi says the lights can still appear until around mid-April, with the chance falling as the evenings get lighter. From mid-April to late August the nights are too light.

FMI names February to March and September to October as the strongest months, and its page on auroras in Finland adds that March and early April are the strongest time in the north. FMI’s statistics show auroras slightly more frequent in spring and autumn than in midwinter, and NOAA also points to the weeks around the spring and autumn equinoxes.

December and January have the longest nights. That gives you more hours to watch, though no more activity. Every window costs you something:

• September and October: aurora nights without deep cold, and calm lakes that can reflect the lights, but no snow to rely on. See Lapland in September and Lapland in October.
• February and March: strong months with snow on the ground and longer days, but cold nights. See Lapland in February and Lapland in March.
• December: the longest darkness and the Christmas crowds. See Lapland in December.

For the whole year, month by month, see when to go.

What causes the Northern Lights

The source is the Sun. FMI explains that particles leave the Sun all the time, in a stream called the solar wind, and some of them end up in the Earth’s atmosphere. There, electrons plunging down along the Earth’s magnetic field collide with oxygen atoms and nitrogen molecules in the ionosphere. Each collision lifts the atom or molecule briefly into a higher energy state, and as it falls back the energy is released as light. FMI compares the process to a fluorescent tube.

The colour depends on what is hit: oxygen gives green and red light, nitrogen a bluish one. FMI places the light itself at about 100 to 200 km above the ground; NOAA’s wider range for where the aurora forms is the one given at the top of this page.

The oval of light is there all the time, over both hemispheres. FMI notes that daylight hides it, except in the darkest polar-night areas in winter, and that most of it lies over uninhabited areas. The time of year matters too: around the spring and autumn equinoxes, FMI says, the Earth’s position in the solar wind is at its most favourable for the wind’s energy to pass into the Earth’s magnetic field, which is one reason the equinox months appear in the season above.

Can you see the Northern Lights with the naked eye?

You can. FMI says faint aurora light shows best to the naked eye under a clear, dark sky, away from the lights of towns and traffic. Don’t expect it to look like the photographs, though. NOAA says modern digital cameras are often more sensitive than the human eye, and can record an aurora and its colours when it is too dim for you to see. In dim light the eye picks out brightness before colour, which is why people often describe a faint aurora as pale white. Only a fairly bright display shows its true green or red to the naked eye.

The most common colour is a pale green, and red is less common. FMI lists green, red and violet as typical colours, and says the aurora looks paler to the eye than in photographs because the eye separates colours poorly in dim light.

FMI adds two practical points. Full night vision takes tens of minutes, so give your eyes time. And photographs need a camera with full manual controls; the settings, and what a phone can manage, are in how to photograph the Northern Lights.

The Northern Lights forecast, and how to read it

No forecast can tell you on booking day whether a given night will have an aurora. FMI says auroras cannot be reliably predicted, and estimates only the chance for the coming nights. NOAA says an accurate forecast is possible only a short time ahead, measured in minutes, from measurements of the solar wind before it reaches the Earth. Forecasts are for the day itself and no help in choosing dates.

How to read one, from the Kp index to FMI’s yellow and red station readings and the cloud map, is on its own page: how to read a Northern Lights forecast. The short version for a night in Lapland is to check the cloud first, then the magnetometer station nearest you.

• FMI auroras and space weather: the chance of auroras in Finland, from FMI’s own magnetometer stations.
• Space weather in Finland: FMI’s live geomagnetic activity, an aurora probability map, and an all-sky camera in Muonio.
• NOAA 30-minute aurora forecast: the short-term view of where the aurora is and how bright.
• FMI weather forecast for Rovaniemi: its weather symbols show whether clear or cloudy skies are expected, which matters as much as activity.