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When is it a heat wave in Denmark?

Three hot days in a row

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Short answer

A heat wave (hedebølge) in Denmark is when the average of the highest temperatures over three days in a row is above 28 °C in the same place. DMI issues a level 1 warning at that point and a level 2 warning when the three day average of the highest temperatures is above 30 °C. In heat, stay in the shade, especially between 12.00 and 15.00, wear a hat and light, loose clothes, and drink plenty of water even when you are not thirsty. Older people, children and toddlers are most at risk.

Weather and seasons

Why

  1. Heat stroke builds up slowly, so you notice it late.
  2. The body loses a lot of fluid through sweat on hot days.
  3. Older people, children and toddlers are the most vulnerable.

Details

Besides water, it helps to drink or eat something salty in the heat.

Tip

Go easy on alcohol on hot days, because it raises the risk of heat stroke.

What may differ

Heat wave warnings come at most 36 hours ahead, so the exact days are known only shortly before.

Common misconception

Denmark never gets hot enough to be dangerous.

What actually happens

In June 2026 a heat wave brought more than 30 °C to many places, and heat can be risky for vulnerable people.

People also ask

  • How hot does it get in Denmark in summer?
  • Do hotels in Denmark have air conditioning?
  • What should you do in a heat wave?

Sources

This answer is for reference only. Weather varies a lot from year to year, so check the DMI forecast before you travel.

Weather and seasons
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