April in Flagstaff averages a daily high of 15.1°C with nights around -2.1°C. Expect roughly 4.9 wet days totalling 21mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Flagstaff is May–June.
Based on FLAGSTAFF AIRPORT, AZ US (6.1km), 1995–2024. 30 years of April data.