May in Vacaville averages a daily high of 27°C with nights around 11°C. Rain is rare — about 2.9 wet days and 16.8mm across the month. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Vacaville is April–May.
Based on VACAVILLE NUT TREE AIRPORT ASOS, CA US (3.4km), 1995–2024. 27 years of May data.