The “mistral” is a local wind which affects southern France. It is driven by the circulation around high pressure. The flow forces air down from high elevations towards the coast. As the air sinks, it clears and dries up, helping to provide cloudless days and low humidity that are great for growing grapes in the region.
VinePair has a short article on the mistral that explains why it helps create unique wines like roses from Provence at https://vinepair.com/wine-blog/the-mistral-it-aint-just-some-silly-breeze-its-what-makes-french-wine-awesome/.