According to the U.S. Census Bureau, the county has a total area of 789 square miles (2,040 km²), of which 748 square miles (1,940 km²) is land and 40 square miles (100 km²) (5.1%) is water.

Napa is warmer in the summer than Sonoma County, to the west, or Santa Barbara County, a wine-producing county in southern California.
Thus, the Napa wineries favor varietals such as Cabernet Sauvignon, while Pinot noir and Chardonnay are more the specialty of Sonoma and Santa Barbara wineries.
At the north end of Napa County, in the Mayacamas Mountains, lies Mount Saint Helena, the Bay Area's second tallest peak at 4,344 feet (1,323 m) and home to Robert Louis Stevenson State Park; Snell Valley is also situated in northern Napa County; the Missimer Wildflower Preserve is within Snell Valley.
On the west side of the Napa Valley is Hood Mountain, elevation 2,750 feet (838 m).

Napa County is home to a variety of flora and fauna including numerous rare and endangered species such as Tiburon Indian paintbrush and Contra Costa goldfields.
According to the U.S. Census Bureau, the county has a total area of 789 square miles (2,040 km²), of which 748 square miles (1,940 km²) is land and 40 square miles (100 km²) (5.1%) is water.
Napa is warmer in the summer than Sonoma County, to the west, or Santa Barbara County, a wine-producing county in southern California. Thus, the Napa wineries favor varietals such as Cabernet Sauvignon, while Pinot noir and Chardonnay are more the specialty of Sonoma and Santa Barbara wineries. At the north end of Napa County, in the Mayacamas Mountains, lies Mount Saint Helena, the Bay Area's second tallest peak at 4,344 feet (1,323 m) and home to Robert Louis Stevenson State Park; Snell Valley is also situated in northern Napa County; the Missimer Wildflower Preserve is within Snell Valley. On the west side of the Napa Valley is Hood Mountain, elevation 2,750 feet (838 m).
Napa County is home to a variety of flora and fauna including numerous rare and endangered species such as Tiburon Indian paintbrush and Contra Costa goldfields.
Napa County, California