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Todays Northern Lights Forecast

Todays Northern Lights Forecast

Back in the day we gave gods and magical creatures credit for the Northern Lights, today we are using science to maximize our chances to see the natural phenomenon. How strong and if the lights appear on the sky is dependent on many factors, e.g. solar wind speed and the strength of the disturbance that is caused by solar wind. One of the key factors is of course the cloud coverage. The Northern Lights shine at their best when the sky is dark and partly clear.

All our guides have years of experience when it comes to reading and interpreting forecast systems for the Northern Lights and we will share some of the most useful sources and information with you here on this site. 

Best forecast websites

One of our all-time favourites is a website created from some of the best icelandic weather specialists -

If you want to get plenty of real live information about the magnetic field, solar wind speed, KP-Index we recommend -

A less scientific but still very useful forecast is provided by the Icelandic Met Office -

“Script from Vedur/cloud coverage and KP index here:”

How to interpret the data

KP Index

The KP-index describes the disturbance of the Earth’s magnetic field caused by the solar wind. The faster the solar wind blows, the greater the turbulence. The index ranges from 0, for low activity, to 9, which means that an intense geomagnetic storm is under way. 

  • Kp 0 – Quiet – Aurora oval mostly to the north of Iceland. Faint aurorae visible in photographs, low in the northern sky
  • Kp 1 – Quiet – Aurora oval over Iceland, faint and quiet aurorae visible to the unaided eye low in the northern sky
  • Kp 2 – Quiet – Auroras readily visible and become brighter and more dynamic
  • Kp 3 – Unsettled – Bright auroras visible at zenith. Pale green colour more obvious
  • Kp 4 – Active – Bright, constant and dynamic northern lights visible. More colours start to appear
  • Kp 5 – Minor storm – Bright, constant and colourful aurora display, red and purple colours appear. Aurora coronae likely
  • Kp 6 – Moderate storm – Bright, dynamic and colourful aurora display. Aurora coronae likely. Memorable to those who witness them
  • Kp 7 – Strong storm – Bright, dynamic and colourful aurorae. Visible in the southern sky. Aurora coronae very likely
  • Kp 8 – Severe storm – Bright, dynamic and colourful aurorae. Aurora seen around 50° latitude
  • Kp 9 – Intense storm – Aurorae seen around 40° latitude. Red aurorae and coronae are very likely. Most often caused by powerful coronal mass ejections.

Please note that the KP-Index can’t predict the strength of the Northern Lights, but it is still a great indicator about what we can expect during our hunt.

Solar Wind Speed 

The solar wind is a stream of charged particles, mostly electrons and protons, flowing from the Sun. The faster the solar wind is moving, the likelier you are to see an intense northern lights display. The solar wind speed is measured by the DSCOVR satellite 1.5 million kilometres from the Earth.

The speed of the solar wind varies. The normal steady stream of the constant solar wind is roughly 300 km/s (186 mps), but the fast-moving solar wind, flowing from coronal holes in the solar corona, is usually between 500-800 km/s (300-500 mps). When the wind speed reaches this threshold, geomagnetic storms are very likely to occur. Auroras can then become very bright, colourful and dynamic.

The solar wind causes Earth’s magnetic field to rattle. This rattling is observed by magnetometers like at the Leirvogur Magnetic Observatory. That causes solar wind particles stuck in the magnetosphere to flow along the field lines towards the polar regions of Earth. There, the solar wind particles collide with oxygen and nitrogen atoms and molecules in the upper atmosphere, causing it to glow which gives birth to the Northern lights.

Interplanetary Magnetic Field

The solar magnetic field not only surrounds the Sun itself, the solar wind carries it out into the solar system to form the interplanetary magnetic field or IMF.

The strength of the interplanetary magnetic field is given a value called Bt and is measured in nanoTesla (nT). The north-south direction of the interplanetary magnetic field (Bz) plays an important role in the formation of Northern Lights. When the north-south direction of the IMF flips south, the magnetic field lines connect to the earth’s magnetosphere which faces north.  A rift opens that allows the solar wind to pour into our magnetosphere. Bz becomes negative, for example –10nT, which is a good sign that auroras will start to appear.

So, when you are out chasing the northern lights, watch the orientation of the IMF closely. When it flips south, odds are that northern lights are visible overhead.