Sea temperature in Thailand
Live water temperatures and swimming conditions across 122 beaches on the Thailand coast.
Best time to swim in Thailand
The sea in Thailand peaks in April, when the water averages around 30°C.
The main swimming season runs from January – December, when surface temperatures stay comfortable for extended sessions.
On average, 12 months a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
The coldest month is typically January at around 27°C, when cold-water swimmers dominate the coast.
Thailand sea temperature history
Long-term climatology for Thailand shows an annual mean sea temperature of 29°C, ranging from 27°C in winter to 30°C at the summer peak.
The seasonal swing is roughly 3°C between the coldest and warmest month — a useful yardstick when comparing years or checking whether the current sea is running above or below average.
Recent decades have trended slightly warmer at Thailand, in line with regional sea-surface temperature records for the wider basin.
Monthly averages below are drawn from multi-decadal climatology and are updated as new observations arrive.
Values are area averages; individual beaches vary by exposure and depth.
Thailand sea temperature: frequently asked questions
What is the warmest month to swim in Thailand?
April is the warmest month in Thailand, when the sea averages about 30°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in Thailand?
The coldest month in Thailand is typically January, when the water averages around 27°C. Cold-water swimmers and surfers dominate this period.
When can you swim in Thailand without a wetsuit?
The main swimming season in Thailand runs from January – December — about 12 months a year when the sea sits above 20°C, the level most swimmers describe as pleasant without a wetsuit.
Do I need a wetsuit in Thailand?
Thailand stays warm year-round, so most swimmers never need a wetsuit — a rash guard is usually enough for sun and wildlife protection.
What is the average sea temperature in Thailand?
The long-term annual mean sea temperature in Thailand is about 29°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in Thailand?
The live reading at the top of this page shows the current sea temperature in Thailand, updated hourly from marine buoy and satellite data. The 7-day forecast covers water, air, waves, wind and UV for the week ahead.
Coastal regions of Thailand
Region hubs with live sea temperatures, swim conditions and a beach directory.