Koh Samui Weather: Seasons, Coasts & Rain Planning
Koh Samui weather by season, east vs west coast, and how to plan around rain, wind and boat trips. Check live forecasts before you go.
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Last updated November 2026. Koh Samui weather depends mainly on monsoon timing and on which coast you stay on, and afternoon showers are hard to pin down far ahead. Use live forecasts for the next few days, then use this guide to turn the seasonal pattern into booking decisions.
Featured image: Christophe95, CC BY-SA 4.0, via Wikimedia Commons.
Koh Samui weather at a glance
Samui sits in the Gulf of Thailand, so rain, wind and sea state shift with the monsoon. Wetter, rougher conditions cluster in the autumn months, and drier, calmer conditions arrive from about December. Confirm monsoon timing and warnings on the Thai Meteorological Department site. November is humid, with frequent light rain and the occasional heavy burst. A recent morning reading showed 27°C (81°F), feeling like 29°C (84°F), with a forecast high of 30°C (86°F) and humidity around 82%. Treat that as the typical feel, not a forecast. For this week, check a live forecast tool rather than a static page.
Weather by season
Pick your dates by the pattern below, then read our full best-time guide for the wider decision. Temperatures stay warm all year, with feels-like readings often several degrees above air temperature. A forecast high of 30°C (86°F) can feel closer to 33°C (91°F) in humid air. Rain and sea state change far more than heat does.
| Period | Typical conditions | Sea and boat-trip outlook | Best fit for |
|---|---|---|---|
| Dry season (about December onward) | Less rain, more sunshine, calmer air | Generally calmer; fewer cancellations | Beach-focused trips, snorkelers, short stays |
| Shoulder months | Mixed sun and afternoon showers | Variable; check day by day | Flexible travelers, mixed itineraries |
| Wet months (autumn monsoon) | Frequent rain, high humidity, heavy bursts | Rougher; cancellations more likely | Budget travelers, long stays with buffer days |
East coast vs west coast: which side to stay on
Conditions can differ between coasts on the same day. Chaweng and Lamai face east, while Nathon sits on the island's other side. Wind direction shifts with the monsoon, so one shore can be choppier than another. Check a local forecast for your exact area before you choose a base. Accept a trade-off: the calmer shore may mean a different beach style and a different distance to the airport and ferry piers. Verify those distances on a map before booking.
How to read a Koh Samui forecast
A rain percentage is the chance of measurable rain at some point, not the share of the day that is wet. Afternoon convective showers are hard to predict beyond about 48 hours. Recheck 48–72 hours before any non-refundable activity. Match the tool to the job: use TMD for official warnings, Windy for wind and waves, and Yr or MSN for hourly detail. Hourly tables show light rain on many November days, so read the totals rather than a single icon.
Wind, sea state and boat trips
Operators decide on sea state and wind. Confirm with your operator or the Ang Thong park authority on the day. Book boat trips early in your stay so a cancelled day has slack behind it. Ask about the refund policy before paying. Morning departures are often a sensible choice, but confirm local conditions rather than assuming calm mornings. If you arrive from the mainland, leave buffer time around airport and ferry connections in rough weather.
Book boat trips early so a cancelled day has slack, then recheck the forecast 48–72 hours before departure.
- Ang Thong day trip: high weather risk
- Snorkeling: medium to high risk
- Scooter ring road: medium risk, higher on wet roads
- Temple visits: low risk
- Night markets: low risk
If it rains: plan B
Rain rarely ends a Samui trip. Covered options include cooking classes, spa sessions, temple visits, shopping malls in Chaweng and covered walkways at Fisherman's Village. Prices vary by operator, so check current rates directly. Our rainy season guide covers more wet-day ideas. Skip the scooter on wet roads if you are not confident riding. Taxis or a hotel transfer cost more but remove the risk. For scale, one booking platform lists Koh Samui to Koh Phangan ferries from ฿200. Lodging and tour prices move more with season, so compare quotes for your dates.
What to pack and book flexibly
Pack a lightweight rain layer, quick-dry clothes, waterproof phone protection and reef-safe sun protection. Wet-season lodging is usually cheaper, but outdoor days become less predictable. A shorter stay raises the odds of losing a key outdoor day, so add buffer days.
- Book now: flights, lodging with free cancellation, airport transfers
- Wait until 48–72 hours out: Ang Thong trips, snorkeling, scooter days
- Families with young children: prioritize covered options and calmer shores
- Divers and snorkelers: stay flexible on dates and operators
- Honeymooners: choose refundable villas
- Budget travelers: accept rain risk, book cheaper wet-month stays
Month-specific pages to read next
Planning the dry-season start? Read about Koh Samui in December: Weather, Crowds and Costs. Traveling mid-year? See Koh Samui in July: Weather, Crowds & What to Expect. November sits between the two, so expect humid days, frequent light rain and improving odds as the month goes on.
Frequently Asked Questions
Does it rain a lot in Koh Samui?
Rain is common, and it is concentrated in the wetter autumn months. Dry-season months see far less. Check TMD climate data for verified rainfall figures.
Is May wet season in Thailand?
On Samui, May usually brings more frequent afternoon showers as conditions shift toward the wetter months. Mornings can still be fine. Check TMD for this year's monsoon onset.
Useful notes for your Thailand trip
Optional updates to our guides.
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