Home » Weather » Monsoon
Monsoon Risk Optimizer
Thailand has three monsoon patterns and they hit different regions differently. A trip in October is fine for Bangkok but cancels ferries to Koh Tao. This tool computes the impact per region per month.
Inputs
What this solves
Whether to book the trip or shift dates by a month. The Gulf vs Andaman distinction is critical: Phuket is wet in May–Oct, while Koh Samui is wet in Nov–Dec.
How to read
- Expected rain days = month risk × region modifier × days. 3 rain days in 7 is average June Bangkok.
- Ferry cancellation probability: Gulf 30%+ Nov–Dec, Andaman 20%+ May–Oct.
- Burning season (Mar–Apr Chiang Mai): smoke, AQI 200+. Different problem.
- Best overall: Nov–Feb (cool, dry). Worst: Aug–Oct (most rain).
Limitations
- Climate change is shifting patterns — the "dry" months are getting wetter.
- Typhoons (rare in Thailand) can hit Andaman Sept–Nov with very heavy rain.
- Bangkok floods occur Sept–Oct; some low-lying districts 50+ cm water.
FAQ
Why is Gulf coast wet in Nov–Dec while Andaman is dry?
The monsoon retreats south through Nov, hitting Koh Samui / Phangan / Tao last. Phuket dries earlier.
Should I avoid August?
Not necessarily. August hotels are 30% cheaper. Rain comes in 30–60 min bursts, not all day. Inland (Chiang Mai) is fine. Island ferries are the real risk.