May in Gaithersburg averages a daily high of 22.6°C with nights around 11.5°C. Expect roughly 11.8 wet days totalling 111.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Gaithersburg is August–October.
Based on DAMASCUS 3 SSW, MD US (13.8km), 1995–2024. 28 years of May data.