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Northern Lights Forecast

How to read the Northern Lights Forecast in Iceland


I work at the What’s On Tourist Information Office in Reykjavik, Iceland, and quite often people come who don‘t understand the Northern Lights Forecast (aurora forecast) published by the Iceland Meteorological Institute. And really, I can see why, if you’re not used to looking at this kind of thing, so I decided to write this blog to explain it all.

If you find the whole thing confusing, there are two things you should know: if you book a tour, the tour company will cancel the tour if the forecast is really bad. You will be entitled to a refund, so there is really no risk involved. Secondly, you can just come into our office any time and we’ll help you figure it all out for free!<

So let’s begin by looking at the actual Northern Lights Forecast.

Northern Lights Forecast

There, how’s that?

Now, there sure is a lot going on in this picture, isn’t there? Colours and numbers and what have you. So let’s get started:

Looking at the map, Reykjavík is close to the bottom left corner.

What do the colours mean?

On this map, WHITE means NO CLOUDS, and DARK GREEN means VERY CLOUDY. The different shades of green then mean more, or less, cloudy. (Why the meteorological institute chose green – the colour of the northern lights – to represent clouds, is a mystery, but who are we to argue with their choices?)

So, as you can see, on this particular day, there are no clouds in the North of Iceland, heavy clouds in the East, and light clouds in the South.

Why do the clouds stop me seeing the Northern Lights?

The lights are active very high up in the sky. 60-200 miles in fact! The clouds are lower down, so they get in the way and block your view. Unless you’re flying. Which is one way to do it, I guess.

Does the sky have to be completely clear to see the Northern Lights?

No. In fact, often when the Northern Lights forecast says “light green,” meaning it’s a little bit cloudy, all the tours will take off anyway. They aim to find a gap in the clouds and through there you can easily see the lights.


How active are the lights?

On the right side of the picture, you can see the word “Aurora forecast” and underneath you see the numbers 1-9. One of the numbers is highlighted with a rather ugly mustard colour, on this picture it’s the number “2”.

Northern Lights Forecast

Like that, see?

Now, on a scale of 0-9, they’re predicting an activity level of 2. OK, what does that mean?

What do the Activity Level Numbers mean?

What the number is, is a COMBINATION of how PROBABLE the lights are to come out at all, and how ACTIVE they will be when they do come out. What it doesn’t say is exactly what time they will come, or how long they will stay. They could come out at 10 pm or 1 am, and they could stay for 5 minutes or 5 hours.

For instance, I once went out on a prediction of 9 and the lights were out all right, they were out the whole evening, all across the sky. But they were “only” white, not green or red or purple. Someone told me that later in the night they started dancing and turning different colours. So you never know!

This is what you need to know: 85% of the time the Northern Lights forecast is 2 or 3. And even if it’s just 1, it’s still worth going out.

In my experience of looking at this Northern Lights forecast every winter day for the last two years, this is what I’ve learned. There are three reasons for this:

  1. The scientists at the meteorology institute are very cautious with their activity prediction. It almost never goes above 6 or 7. I’ve seen a 7 predicted maybe three times, and a 9 TWICE, literally. So an activity of 2 or 3 is actually fantastic. And 4 or 5 is MIND BLOWING.
  2. The cloud prediction is a lot more reliable than the activity prediction. If the sky is clear and the prediction is 1, you have a chance to see the lights, and you should take it.
  3. If you’ve never seen the lights, an activity of 1 is more than you’ve ever seen, so it will be awesome, even if some other night it’s even more colourful.

The bottom line: If the Tours are going, you should go.


There are many tours taking you out of the bright city lights for a better chance of seeing the Aurora. These tours will be CANCELLED if there is no chance of seeing the lights.

All the major operators can be relied on to do this, first of all because there is a high standard of professionalism in Iceland, but more importantly because they lose money if they take you out needlessly – most of them promise to take you out again for free if you don’t see anything.

So whether you’re actually going on a tour or driving yourself; take your cue from the professionals.

Things to keep in mind in regards to the Northern Lights forecast:

  • It’s not an exact science. There’s always a certain amount of guesswork and luck involved in finding the lights – and if you think about it, isn’t that part of the charm? And even if the forecast is terrible, keep your eyes to the sky, cause you never know.
  • It’s a surprisingly exact science. I’m constantly amazed by how accurately these scientists can predict the cloud cover, including where the clouds are and what time of night they move. So for the most part; do trust the forecast.
  • The further in advance, the less reliable the Northern Lights forecast. If you’re looking 4 days ahead, you want to check again on the day. If it’s good tonight, don’t wait for tomorrow: go tonight. And if you’re booking months in advance, get in touch with us the day before you arrive to see how the outlook is.

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