How many letters does the top answer for “a warm dry wind that blows down the northern slopes of the alps” have?

The most common answer is foehn (5 letters).

Crossword clue: a warm dry wind that blows down the northern slopes of the alps

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

foehn 5 letters wn-def

a warm dry wind that blows down the northern slopes of the Alps

fohn 4 letters wn-def

a warm dry wind that blows down the northern slopes of the Alps