What is haar and why does it happen in summer?

Haar is cold sea fog that forms when warm air drifts over the cold North Sea and cools rapidly, causing moisture to condense. It's most common April through September because that's when there's a big enough temperature difference between the warm land air and the stubbornly cold sea.

How far inland can haar travel from the coast?

It depends on the wind direction and strength. A light easterly wind might only affect coastal areas, while stronger easterly flow can push it miles inland. If the wind shifts to westerly, it'll push the haar back out to sea or prevent it from reaching land at all.

How can I tell if haar is going to ruin my day on the east coast?

Check the wind forecast — easterly or north-easterly winds will bring haar inland, while westerly winds push it back out. Also look for coastal temperatures forecast to be several degrees cooler than inland areas, which usually means haar is happening.

Weather The Elements

When Scotland's Haar Rolls Inland: Forecasting Sea Fog

North Sea fog doesn't always stop at the shore. How wind, temperature and pressure decide whether a haar burns off or settles in for days.

15 September 20268 min read

When Scotland's Haar Rolls Inland: Sea Fog Forecasting | TrailTrack