July in Napa averages a daily high of 28.6°C with nights around 13.1°C. Rain is rare — about 0 wet days and 0mm across the month. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Napa is April–October.
Based on NAPA STATE HOSPITAL, CA US (2.8km), 1995–2024. 30 years of July data.