Gulf of Thailand weather and tide forecast: what the outlook covers
This Gulf of Thailand weather forecast (Samui/Phangan/Tao/Surat Thani) covers 2 July to 7 July 2025, with daily temperatures, sky conditions, sailing notes and tide times for the main ferry corridor between the Surat Thani mainland and the three islands.
Use it as a planning aid alongside your operator's own updates. Conditions in the Gulf can shift within a few hours, so the notes below describe general trends rather than guaranteed sailing outcomes.
Daily forecast, 2–7 July 2025
Wednesday, July 2
Temperature: Highs around 32°C, lows near 26°C
Weather: Overcast with periods of rain
Sailing Conditions: Choppy seas; caution advised
Tide: High at 2:39 AM (2.04m), Low at 10:58 AM (0.93m)
Thursday, July 3
Temperature: Highs around 32°C, lows near 27°C
Weather: Mostly cloudy with late-day thunderstorms
Sailing Conditions: Rough seas; consider postponing trips
Tide: High at 2:49 AM (1.82m), Low at 10:40 AM (0.97m)
Friday, July 4
Temperature: Highs around 33°C, lows near 27°C
Weather: Mostly cloudy with afternoon thunderstorms
Sailing Conditions: Unstable; monitor weather updates
Tide: Low at 10:22 AM (0.98m), High at 7:11 PM (1.84m)
Saturday, July 5
Temperature: Highs around 33°C, lows near 27°C
Weather: Mostly cloudy with afternoon thunderstorms
Sailing Conditions: Unstable; monitor weather updates
Tide: Low at 10:07 AM (0.95m), High at 7:40 PM (1.99m)
Sunday, July 6
Temperature: Highs around 33°C, lows near 26°C
Weather: Cloudy and breezy with brief afternoon showers
Sailing Conditions: Improving; remain cautious
Tide: Low at 9:36 AM (0.90m), High at 8:16 PM (2.13m)
Monday, July 7
Temperature: Highs around 34°C, lows near 26°C
Weather: Mostly cloudy with afternoon rain
Sailing Conditions: Moderate; favorable for experienced sailors
How the week changes
The unsettled stretch sits in the middle of the period. Thursday is the single day flagged for rough seas, with Friday and Saturday both described as unstable. From Sunday the trend turns to improving, and Monday reads as moderate, with the week's warmest high near 34°C.
Tide timing also shifts across the week. Early on, the high water falls in the small hours and the low around late morning; by Friday the pattern moves to a late-morning low followed by an evening high, rising to 2.13m by Sunday evening.
What this means for your trip
Rough or unstable conditions mainly affect crossings between the mainland and the islands, and the shorter island-hopping legs. Smaller, faster craft feel the swell more than larger vessels, so if you are sensitive to motion, a morning departure before the afternoon thunderstorms build is usually the calmer choice.
- Allow buffer time before onward flights or connections during unsettled days.
- Keep the contact details from your booking confirmation to hand for cancellation or rescheduling notices.
- Check departure status on the day of travel — operators, not this forecast, make the final call on sailing.
- Pack a dry bag for luggage carried on open decks during rain.
Routes affected
Conditions here apply to travel around Koh Samui, Koh Phangan, Koh Tao and Surat Thani, including combined tickets that pair a land transfer with a sea crossing. Available services, departure times and prices vary by date and provider, so check the live results for your exact travel day.
Disclaimer: Weather, sea conditions, and tide information are subject to change. Always check local updates and forecasts before planning activities.
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