What the Gulf of Thailand forecast covers
This weather and tide forecast for the Gulf of Thailand covers Koh Samui, Koh Phangan, Koh Tao and the mainland gateway of Surat Thani for Jan 13, 2025 – January 19, 2025. Use it alongside your ferry, bus, minivan or transfer booking to see how conditions may affect your crossing.
Weather Forecast for Gulf of Thailand (Samui/Phangan/Tao/Surat Thani) Jan 13, 2025 – January 19, 2025
Monday, January 13
Temperature: High 28°C (82°F), Low 24°C (76°F). Weather: Cloudy and breezy morning; partly sunny afternoon. Sailing Conditions: Moderate wave heights.
Tuesday, January 14
Temperature: High 29°C (84°F), Low 25°C (77°F). Weather: Partly sunny. Sailing Conditions: Generally calm seas.
Wednesday, January 15
Temperature: High 30°C (85°F), Low 26°C (78°F). Weather: Pleasant and partly sunny. Sailing Conditions: Favorable for boating.
Thursday, January 16
Temperature: High 28°C (83°F), Low 26°C (79°F). Weather: Morning rain, breezy with brief showers in the afternoon. Sailing Conditions: Increased wave activity due to breeze.
Friday, January 17
Temperature: High 30°C (85°F), Low 25°C (78°F). Weather: Breezy morning; pleasant with clouds and sun. Sailing Conditions: Moderate seas, generally safe.
Saturday, January 18
Temperature: High 30°C (86°F), Low 24°C (76°F). Weather: Sunny with areas of high clouds. Sailing Conditions: Calm waters, ideal for activities.
Sunday, January 19
Temperature: High 29°C (84°F), Low 26°C (78°F). Weather: Mostly cloudy. Sailing Conditions: Mild waves, suitable for boating.
Important Note
The strong northeast monsoon prevailing over the Gulf and the South will weaken, resulting in less rain in the lower South. However, waves in the Gulf are expected to remain 2-3 meters high, with heights exceeding 3 meters during thundershowers. Exercise caution during marine activities.
What changed this week
The headline change is the weakening northeast monsoon. Rain eases across the lower South, and the calmest window falls mid-week, with Wednesday and Saturday looking best for boat travel. Thursday is the least settled day, with rain and a breeze building wave activity.
Swell does not drop as quickly as rainfall, so the sea can stay lively even under sunny skies. That is the main reason a bright morning can still bring a bumpy crossing.
Who this affects
Sea conditions matter most to passengers on the island crossings between Surat Thani, Koh Samui, Koh Phangan and Koh Tao. The Koh Tao legs sit furthest offshore and are usually the first to feel bigger swell.
Road-based services are affected differently: buses, minivans and private transfers on the mainland keep running in rain, though heavy downpours can slow journeys and knock on to a connecting boat departure.
Practical impact for travellers
- Leave a generous buffer between a mainland transfer and a boat departure on breezy days.
- Book earlier departures where possible, as afternoon showers and breeze often build later in the day.
- If you are sensitive to motion, choose a mid-week crossing and sit low and central on board.
- Check operator updates on the day of travel — departures can be adjusted or cancelled in rough seas.
- Review the cancellation and change conditions shown at checkout before you pay.
Plan your crossing
Live timetables, operators, journey times and prices for each departure are shown in the search results, so compare the options for your travel date rather than relying on this page for schedules. Popular connections include Surat Thani to Koh Samui ferries, Koh Samui to Koh Phangan crossings and Koh Phangan to Koh Tao services.
Disclaimer: Weather, sea conditions, and tide information are subject to change. Always check local updates and forecasts before planning activities.
Note: no tide table data was supplied for this period, so specific high and low tide times are not listed here.
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