weather in napa, ca october
Average Weather in Napa California, United States. Napa has a mediterranean climate with dry warm summers and mild winters. The temperature typically varies from 39Â°F to 83Â°F over the course of the year, and is rarely below 30Â°F or above 92Â°F. The warm season lasts for 135 days, from May 31 to October 13, with an average daily high temperature above 77Â°F.