September · Vietnam
Best time to visit Phong Nha in September Weather, crowds & prices
Weather in Phong Nha in September
Average temperature 26°C, 532 mm of rain, about 14 days with 6+ hours of sunshine and 88% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
3.4/10
Ranked #12 of 12 months
- Avg temp
- 26°C
- Rainfall
- 532 mm
- Humidity
- 88%
- Days with 6h+ sun
- 14
- Crowd Density
- Quiet / Uncrowded
- Average Expenses
- $ · Budget Friendly ($)
September in Phong Nha scores 3.4/10 for nature and wildlife travel - ranked #12 of 12. Expect around 26°C, 532 mm of rain, and roughly 14 days with 6+ hours of sunshine this month.
Phong Nha anchors the world's largest cave country with Son Doong expeditions and river cave boats. Best window: the drier months outside peak monsoon.
September in Phong Nha — off-season conditions
September averages 26°C (79°F) and humidity near 88%, so the practical pattern is early mornings, a long midday break, and evenings back outside.
532 mm of rain puts this in monsoon territory — about 14 days with 6+ hours of sunshine across the whole month, and multi-day washouts are normal.
It scores 3.4/10 here, 12th of 12 months, against 7.3/10 in the destination's best month.
Pack the lightest breathable clothing you own, a hat, and more water than feels necessary, a proper rain shell rather than an umbrella, footwear you can get muddy.
Plan for low-season pricing, with crowds are light for this destination.
Flexible dates? March scores 3.9 points higher here — enough to change the trip.
Frequently asked
- What is the weather like in Phong Nha in September?
- In September, Phong Nha averages 26°C, 532 mm of rain, and about 14 days with 6+ hours of sunshine. Its climate-comfort score is 3.4/10.
- Is September a good time to visit Phong Nha?
- September earns a 3.4/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Phong Nha in September?
- Expect about 532 mm of rain in September. Average humidity is 88% and there are about 14 days with 6+ hours of sunshine.
Curated in Phong Nha
Tickets & experiences
Things to do in Phong Nha
Phong Nha, Vietnam. Live activities and tours from GetYourGuide, matched to this destination.