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How can I check the sea water temperature before swimming in Denmark?

Sea temperature changes from day to day

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Short answer

You can see current sea temperature measurements and a forecast for the next 48 hours on dmi.dk. In summer DMI also has a bathing water map for beaches with lifeguards, updated around 10.00 each day, which shows temperature, currents and the risk of algae or jellyfish. In 2026 the map covered 54 beaches with lifeguards. In calm, sunny weather around midsummer the water can warm by about half a degree a day, but strong offshore wind can cool it fast: in Frederikshavn in June 2016 it fell from 19 to 9 degrees in one day.

Weather and seasons

Why

  1. The water warms slowly and can cool suddenly.
  2. Strong offshore wind can cool it within a day.
  3. Algae and jellyfish also decide if a swim is pleasant.

Details

Grey, rainy weather cools the sea only slowly, so the water can stay warm for a few days after the sun goes.

Tip

Choose a beach with lifeguards in summer, because you get both safety and a daily water temperature.

What may differ

The list of beaches and the lifeguard season dates change each year.

Common misconception

Once the sea is warm in summer, it stays warm.

What actually happens

One day of strong offshore wind can drop the water temperature by several degrees.

People also ask

  • When is the water warm enough to swim in Denmark?
  • Are there lifeguards on Danish beaches?
  • Are there jellyfish in Denmark in summer?

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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