April in Fullerton averages a daily high of 23.2°C with nights around 12.1°C. Expect roughly 3.1 wet days totalling 15mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Fullerton is April–June.
Based on FULLERTON MUNICIPAL AIRPORT, CA US (5.6km), 1995–2024. 27 years of April data.