Risk of ice-throw

During the winter months, there will be periods when ice forms or snow lies on the wind turbines. Then there is a risk of ice / snow falling or being thrown off. Observe the safety zone of 300 meters that is stated on signs in the wind turbine.

There are several weather conditions that can cause precipitation and throwing of ice and snow from wind turbines. Situations that can lead to a risk of icing or ice / snowfall may be due to ice accumulating on the turbine blades, wet snow settling on the blade, tower or turbine housing or icicles forming due to sub-cooled rain on the turbine. During the winter months, there is always a risk of falling ice / snow from the turbine housing and we therefore recommend avoiding traffic in the immediate vicinity of the turbines.

Factors that may  affect the risk of exposure to icing/ ice fall:

  • The danger increases with proximity to the turbines.

  • Pay special attention when starting up turbines after they have stood still.

  • Check the weather forecast. There is the greatest risk of icing at low cloud cover, when there is or has just been fog or precipitation and at temperatures around 0 degrees.

  • See if you can see ice or snow on the blades or other parts of the turbine. There may also be ice on the tower itself or icicles hanging from the top of the tower.

  • Never stay directly under the turbine.

  • Ice and snow will drift with the wind and if you go near a turbine you should go with the wind at your back

Below is a forecast of the risk of icing in Tonstad Wind Farm. The forecast is based on meteorological data as well as scada data from the turbines and is automatically updated 4 times a day. The forecast cannot be used as a clear indicator that there is no icing as it is based on meteorological forecasts. The notice is intended as a supplement to sign information in order to assess your own risk. The forecast for Tonstad Vindpark indicates the probability that there is ice on the turbines.

What is ice throw?

Atmospheric icing may arise when water droplets in the air freeze when coming into contact with certain objects.

The most common form of atmospheric icing occurs when supercooled water droplets in clouds freeze and turn to ice, attaching to different constructions. Icing may also appear in periods of rain containing supercooled water droplets or wet snow.

These climatic conditions may result in ice appearing on the tower of the wind turbine, the nacelle or the blades.

The climatic conditions may vary a great deal inside a small geographical area, leading to considerable variations concerning the amount of icing on wind turbines found within the same location.

Please note: because of the height difference between the wind turbine and the ground, a layer of ice may develop even if there is no snow or ice on the ground.

Based on a data collection period of 3 years, icing has been shown to form on instruments 7.1 % of the year, corresponding to about 25 days.

Ice that detaches and falls from a wind turbine is referred to as ice throw.

Ice throw may pose a danger to people and animals in the vicinity of the of the turbines. Ice falling from the turbine blades may also lead to minor damages to the turbine itself.

Det er i beregninger antatt at isbitene alltid kastes 90 grader til høyre for vindretningen, med et lite tillegg på 15 grader i vindens retning. Med vind hovedsakelig fra østlig retning under isingsforhold er det i beregningene antatt en stor sannsynlighet for iskast mot nord-nordvest og nord. I realiteten vil det være en relativt stor spredning i kastretningene og bruk av retningsfordelingen kan derfor være noe misvisende.

Sannsynligheten for at en person blir truffet er veldig liten, men om det skjer kan skadeomfanget bli alvorlig.

Sjekk derfor alltid isingsprognosen på hjemmesiden vår før du går inn i vindparken.

Takk for at du samarbeider med oss slik at ingen blir utsatt for unødvendig fare og kan komme til skade.


  • Check risk of ice-throw on our website
  • Hazard increases with closeness to the turbines
  • Recommended safety-distance is 300 meters
  • Consider weather conditions: Risk is much greater when misty and temperatures are around 0 degrees celcius.
  • If you are walking towards a wind-turbine, do it with the wind in your back – then ice will drift with the wind away from you.


We are pleased to announce that Tonstad Vindpark completed its construction phase and started commercial operation on 29 July 2020.

The first six (of 51) turbines in Tonstad wind farm are now producing energy. The assembly and electrification of the remaining turbines is ongoing.

Two turbines in Tonstad Wind farm have now begun to produce electricity. Average production per turbine will be approximately 12GWh per year.

The substation and the 132kV line in Tonstad Vindpark have been electrified.

Contact us

For coordination with Site Manager on guard, contact us by calling the number +47 477 04 435.
For media enquiries, please contact our Stakeholder Manager, Helge Toft, at the number +47 930 64 111