The single most common planning mistake is treating "Southeast Asia" as one climate. It isn't. The monsoon runs on coastlines, not borders — and two beaches in the same country can be having opposite weather in the same week.
| Coast | Wettest | Best | |---|---|---| | West (Penang, Langkawi) | Sep–Oct | Dec–Mar | | East (Perhentians, Tioman) | Nov–Feb | Mar–Sep |
The east coast islands largely close during the northeast monsoon. Boats stop running. A trip planned for Perhentian in December isn't a wet trip, it's a cancelled one.
Andaman side (Phuket, Krabi) is driest November to April. Gulf side (Koh Samui, Koh Phangan) runs later and is wettest in November — the month people book precisely because it's dry everywhere else.
Long and thin, so it's genuinely three climates. The north has a cold winter that surprises people who packed for the tropics. The centre floods around October and November.
Bali's dry season is roughly April to October. July and August are dry and peak season, which means you're paying the most for the most crowded version. May, June and September are the value months.
Pick the region first, then the month — not the reverse. If your dates are fixed, let them choose the destination rather than forcing a destination into the wrong week.
Plan a trip and Mezzo will flag public holidays, seasonal closures and what the forecast actually says for your dates.
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