Weather and Tide Forecast for the Gulf of Thailand (Samui/Phangan/Tao/Surat Thani)

Gulf of Thailand Weather Forecast (Samui/Phangan/Tao/Surat Thani) July 21 to 26 July, 2025.

Monday, July 21

Temperature: ~27–35 °C
Weather: Scattered to fairly widespread thundershowers, isolated heavy rain 
Sailing Conditions: Rough — waves 2–3 m, above 3 m in thunder cells 
Tide: High early morning, low afternoon

Tuesday, July 22

Temperature: ~27–36 °C
Weather: Widespread thundershowers, isolated heavy to very heavy rain 
Sailing Conditions: Rough — similar wave heights (2–3 m, >3 m in storms) 
Tide: Low mid-morning, high late afternoon

Wednesday, July 23

Temperature: ~27–35 °C
Weather: Scattered to widespread thundershowers, heavy rain possible 
Sailing Conditions: Rough — waves mostly 2–3 m, rising to over 3 m in cells 
Tide: Low late morning, high early evening

Thursday, July 24

Temperature: ~27–35 °C
Weather: Scattered thundershowers and isolated heavy rain 
Sailing Conditions: Rough — 2–3 m waves, above 3 m in thunder areas 
Tide: Low early afternoon, rising overnight

Friday, July 25

Temperature: ~28–36 °C
Weather: Scattered to fairly widespread showers, isolated heavy rain 
Sailing Conditions: Rough — consistent with 2–3 m waves, >3 m in storms
Tide: Low midday, high evening

Saturday, July 26

Temperature: ~27–37 °C
Weather: Scattered showers, thunderstorms possible 
Sailing Conditions: Rough — expect 2–3 m waves, over 3 m in thunder cells 
Tide: Late morning low, late evening high

• The southwest monsoon strengthens over the Gulf—wind speeds 15–35 km/h (8–18 knots) (tmd.go.th).

• Expect consistently rough seas; small boats should remain ashore, while larger vessels must steer clear of thunderstorm cells (tmd.go.th).