Koh Samui
Gulf-side alternative to Phuket. Seasons flipped — October–November are the wettest.
A decent stretch with some sun and a chance of a shower.
Days 1–5 are usually reliable, 6–10 drift, 11–14 are the model guessing. Check again the day before you fly — more on what this can and can't do.
When to go
From the 2026 climate study, not the live forecast.Structural odds, not a verdict — the live forecast can still surprise either way.
Gulf-side schedule is flipped from Phuket — driest February through September, wettest October–November (480–560 mm in November). The longest dry-stretch swim destination in mainland SE Asia. Calmer ferry crossings than the Andaman side.
Cheapest return we found: 3–8 Sept · 1+ stops. Live search on Kiwi.
Common questions about Koh Samui
When is the best time to visit Koh Samui?
January–September is when we'd go. Skip October–November: the monsoon. The live forecast on this page shows what the next two weeks look like.
Is Koh Samui worth visiting in June?
Yes. June sits inside the best stretch (January–September). Once your dates fall within the next two weeks, the forecast above gives you the real picture.
Is Koh Samui good in October?
We'd go another month: October means the monsoon. Locked dates? It still works if you plan around short, heavy showers rather than written-off days.
Dates settling? Compare hotels on Booking and flights on Kiwi — both open with the forecast's best window pre-filled.
Hotel and flight links are affiliate links. We earn a small commission when you book; the price is the same for you. We only recommend options we'd use ourselves. Full policy.