The Helm Wind is a type of föhn wind, which is a warm, dry wind that descends down the lee side of a mountain range after being lifted and cooled on the windward side. In this case, the wind descends from the Pennines. The Helm Wind can be quite strong and gusty, with recorded wind speeds of over 100 miles per hour (160 km/h). It is known for its abrupt onset and can shift in intensity rapidly.
The Helm Wind has been documented in historical records dating back centuries and has been a subject of local lore and fascination. In Cumbrian tradition, this wind is associated with Arthur.