May in Rayong averages a daily high of 34.4°C with nights around 25.8°C. Expect roughly 12.6 wet days totalling 151mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Rayong is December–March.
Based on SATTAHIP, TH (29.8km), 1995–2024. 20 years of May data.