May in Ŭndŏk averages a daily high of 16.8°C with nights around 8.2°C. Expect roughly 12.2 wet days totalling 91.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Ŭndŏk is September.
Based on POSET, RS (40.8km), 1995–2024. 29 years of May data.