Devil winds explained

This comes from the Wikipedia entry on Santa Ana winds:

Santa Anas are a type of drainage wind, an offshore wind that results from the buildup of air pressure in the high-altitude Great Basin between the Sierra Nevada and the Rocky Mountains. When upper level winds are favorable, this high altitude air mass spills out of the Great Basin and is propelled gravitationally towards the southern California coastline, generally as a northeasterly wind.

It is often said that the air is heated and dried as it passes through the Mojave and Sonoran deserts, but according to meteorologists this is a popular misconception. The Santa Ana winds usually form during autumn and early spring when the surface air in the elevated regions of the Great Basin and Mojave Desert (the "high desert") becomes cool or even cold, although they may form at virtually any time of year. The air heats up due to adiabatic heating during its descent. While the air has already been dried by orographic lift before reaching the Great Basin as well as by subsidence from the upper atmosphere, the relative humidity of the air is further decreased as it descends from the high desert toward the coast, often falling below 10 percent.