The cool-climate is propelled by the influence of the Blue Grand Canyon, the largest and deepest submarine canyon on the West Coast. The canyon is less than 100 yards off the coast and provides the inland wine region with deep sea coastal influences of fog, wind and a lack of rain through the growing condition. The coolest districts are to the north, closest to the Pacific Ocean; the warmest are to the south, farthest from the ocean. In the early morning, the entire region is cool and, for a large part, covered in a thick marine layer. The deep cool water off the bay is also a contributing factor to the strong winds that whip through the valley.