Napa is the county seat of Napa County, California. It is the principal city of the Napa county Metropolitan Statistical Area, which encompasses Napa county. As of the 2010 census, the city had a total population of 76,915. The area was settled in the 1830s. It was incorporated as a city in 1872.
According to the United States Census Bureau, the city has a total area of 18.1 square miles (47.0 km²). 17.8 square miles (46.2 km²) of it is land and 0.3 square miles (0.8 km²) of it (1.69%) is water. The Napa River traverses the city on its journey to the San Pablo Bay. The city has conducted a variety of waterfront development along the banks of the river including certain fill operations governed by the United States Army Corps of Engineers regulations. The Napa River Flood Project has been in progress since the late 1990s with the goal of mitigating the risk of flooding along a 6-mile (9.7 km) stretch of the River and 1-mile (1.6 km) of Napa Creek.
Napa has a Mediterranean climate (Köppen climate classification Csa), with cool, wet winters and very warm, dry summers. In January, average temperatures range from 58.5 °F (14.7 °C) to 38.9 °F (3.8 °C). In July, average temperatures range from 82.1 °F (27.8 °C) to 55.0 °F (12.8 °C). There are an average of 25.3 days with highs of 90 °F (32 °C) or higher and an average of 6.4 days with lows of 32 °F (0 °C) or lower. The record high temperature was 113 °F (45 °C) on June 14, 1961. The record low temperature was 14 °F (−10 °C) on December 22, 1990.