Thailand Guide

Best time to visit Koh Samui

Koh Samui is known for a January to September Gulf sea that fits a first beach week, while October to December is wetter on the east coast. Keep Phuket boats off that same first week so you are not mixing two monsoons.

Back to Koh Samui
Jan to SepOct to Dec swellOne coast first
Best time to visit Koh Samui
Photo: Fabio Achilli (CC BY 2.0)
Easier seaJanuary to September
Messy GulfOctober to December
Andaman flipNovember to April is the other coast
USM hop10 to 20 minutes to Chaweng any month
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The Lower Gulf is easier January to September, and that is the Samui, Phangan, and Tao window. October to December brings wind and cancelled Ang Thong days, and the Andaman (Phuket, Krabi) is the opposite winter: November to April. Do not put both coasts on a first week.

USM to Chaweng is still 10 to 20 minutes in rain. Book rooms on where to stay before you lock a boat. Pair this page with when to go if the calendar is the only open question.

Month notes

  • Jan to Apr: Dry overlap with the Andaman. Pick one sea.
  • May to Sep: Gulf still works while Andaman boats cancel.
  • Oct to Dec: Swell, park closures, and more boat delays.

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Southeast Asia TravelGuide Network

Compare Across Southeast Asia: Thailand Islands vs. Vietnam Coast

Weighing a Thai island week against Vietnam’s coast, or combining both? Compare water clarity, dry-season months, and five-star beachfront value.

Gulf of Thailand Sister Island

Phu Quoc Island

Shares the exact November to April calm-water window as Phuket and Koh Kood, with sunset beach clubs and luxury pool villas.

Explore Phu Quoc on Vietnam Guide →Central Coast Beach & Heritage

Da Nang & My Khe Beach

Best February to August (matching Koh Samui): broad sandy beaches, Son Tra Peninsula resorts, and 35 minutes to Hoi An.

Explore Da Nang on Vietnam Guide →Remote Archipelago & Diving

Con Dao & Nha Trang Bays

For Koh Tao and Koh Lanta fans seeking protected coral reefs, quiet coves, and hideaway luxury at Six Senses Con Dao.

Explore Con Dao on Vietnam Guide →
Search flights Bangkok to Da Nang BKK to DAD 1h 40m nonstop

Common questions

Is August a bad Samui month?
No. August is a Gulf month. It is a bad Andaman boat month.
Can you do Phuket and Samui in seven days?
You can fly it. You will spend the week in terminals. Pick one coast.