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Northern Lights Forecast

How to read the Northern Lights Forecast in Iceland


Do you want to see the northern lights in Iceland? There are two good online northern lights forecasts that can help you with finding them. One can be found when visiting the website of the Icelandic Meteorological Office and the other when you go to the website Aurora Forecast. Aurora Forecast uses the information gathered from the Met Office but adds more data to it to create a complete overview.

Both forecasts can be a little hard to decipher if you have never seen something like this before. In this article, we would like to make things a little clearer. But 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 the What’s On Tourist Information 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.

It’s important to note that the Aurora Forecast website uses blue to purple for low clouds, orange to red for mid-level clouds and green for high clouds. So don’t get the colours from the two sites confused!

Why do the clouds stop me seeing the Northern Lights?

The lights are active very high up in the sky. 90-150km 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.

In Iceland, low clouds are clouds located up to 2km, middle clouds between 2-4km, and high clouds between 3-8km in altitude. Cloud cover is difficult to predict, and it’s best to look at cloud cover forecasts as late as possible. Looking at a cloud forecast 24 hours ahead will probably not give you reliable information.

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. This is known as the kp index, which tells you how likely it is for the lights to be active and how active they will be. One of the numbers is highlighted with a rather ugly mustard colour, in 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.

Don’t be discouraged if the number is low, it’s actually very rare for the number to be higher than 5. Also, take the scale with a grain of salt; a low number doesn’t mean that they won’t come out or won’t be impressive, and a high number isn’t a guarantee that they will be glorious all through the night.

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 rarely goes above 6 or 7. I’ve seen a 7 predicted maybe three times, and a 9 TWICE, literally. So activity of 2 or 3 is actually fantastic. And 4 or 5 is MIND BLOWING.
  2. Cloud prediction is a lot more reliable than 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.


Many tours are available that take you far from 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 northern lights. Book your northern lights tour here!

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.

Do you want to know how to photograph the aurora? Then read our guide on how to photograph the northern lights.

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 on 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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