Thailand — Sea Water Temperature and Annual Ranges
Up-to-date sea water temperatures for the coasts of Thailand. Learn about today’s conditions, monthly averages, and how the surrounding seas and oceans vary by season. We find every place where you can swim and show you the water temperature there today and throughout the year.
Sea Water Temperature Along the Coast
Chart of Average Temperature Changes Over the Last 60 Days
Places with the Warmest Sea Water Today
The Most Popular Seaside Places
Coastal Seas and Oceans
Water Temperature and Swimming Overview
Regions and Map
Water Temperature Trends
Thailand’s coastal waters are pleasantly warm year-round, making swimming a popular activity for visitors and locals alike. Sea temperatures typically range from about 26–31 °C (79–88 °F) depending on the season and location. During the cooler months, roughly November to February, water temperatures often sit near 26–28 °C (79–82 °F). The hottest period from March to May can push sea temperatures to 29–31 °C (84–88 °F). The rainy season, broadly May to October, usually sees temperatures around 27–30 °C (81–86 °F), though cloud cover and rainfall can make the sea feel cooler.
Swimming Conditions
Swimming is generally allowed and widely enjoyed along both the Andaman Sea and Gulf of Thailand coasts because the water remains warm and accessible. However, conditions vary by coast and season: the Andaman side (Phuket, Krabi) is prone to rough seas and stronger swells during the northeast monsoon (around November–March), while the Gulf coast (Koh Samui, Hua Hin) can be choppier during the southwest monsoon (May–October). Local advisories, beach flags and lifeguard instructions are used to close or restrict swimming when currents, storms, or other hazards are present. In short, warm water makes swimming possible year-round, but seasonal weather and safety warnings determine whether it is advisable at any particular time or place.