May is peak season for Phong Nha — hot weather outside but all caves are fully accessible and naturally cool inside. This is one of the best months for Son Doong Cave expeditions (when they operate), and the park’s swimming holes and jungle rivers are warm and inviting.
Weather in Phong Nha in May
- Temperature: 24–35°C (75–95°F)
- Conditions: Hot and dry; excellent outdoor and cave conditions
Best Things to Do in May
- Son Doong Cave expedition: Peak season for the world’s largest cave
- Phong Nha Cave, Paradise Cave, Hang En
- Nuoc Mooc Eco-Trail: Swimming in crystal-clear karst spring water
- Dark Cave: Zip line, kayak, and swimming
Travel Tips for May
- Son Doong permits sell out months in advance — book immediately when they open
- Hydrate thoroughly in the heat
- May is among the very best months for cave exploration