There is no direct translation into English, possibly because it sounds like a local name for a fairly common weather phenomenon.
For example, here in Southern California we have the "Santa Anas", a dry wind that blows from the Santa Ana desert out over the ocean, and is unfortunately common around late summer / early autumn when everything is already very dry. Small blazes, that would normally be easily extinguished, quickly turn into out-of-control wildfires when the Santa Anas are blowing, which happened with numerous fires just this past year.
Elsewhere few people would know what a "Santa Ana" is, or why it's important to life here, but will understand if you describe it. In the same way the Föhn-Wind is what those in that area call something that may have other names in other regions of the world: The Brookings/Chetco effect, Chinook, Kumagaya, Puelche, Wuhan, Viento del Sur, Nor'Wester, and many others.
Note that "Föhn" (or "Foehn") may be in the dictionary, but then so are many other names of winds from around the world. Knowing these may get you many points when playing Scrabble, but you'll still probably have to explain them in casual conversation.