Wine Spectator School

 
Two Sets of Mountains
Two rugged mountain complexes flank the valley floor. They form the frontiers of Napa winemaking and produce many cutting-edge wines.

 
Mayacamas to the West
The western edge of Napa Valley is bordered by the Mayacamas Mountains. They separate the valley from Sonoma County and the Pacific Ocean, which is 30 miles away.

Since they run parallel to the coastline, the Mayacamas' steep upper slopes catch much of the rain blowing off the ocean. Thanks to the precipitation, the mountains are heavily forested, lush and green.

On summer afternoons, when superheated air starts rising above the Central Valley, chilly ocean breezes make their way through the lower gaps to moderate the temperatures...