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Sea temperature in Thailand

Live water temperatures and swimming conditions across 82 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.

Jan
27°C
Feb
28°C
Mar
29°C
Apr
30°C
May
30°C
Jun
29°C
Jul
29°C
Aug
29°C
Sep
29°C
Oct
29°C
Nov
28°C
Dec
27°C

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.

Thailand sea temperature by month

Average sea temperatures around Thailand for every month of the year, based on long-term Open-Meteo marine climatology.

Monthly average sea temperature in Thailand
MonthAverage sea
January27.0°C
February28.0°C
March29.0°C
April ⭐30.0°C
May30.0°C
June29.0°C
July29.0°C
August29.0°C
September29.0°C
October29.0°C
November28.0°C
December27.0°C

Monthly figures are modelled climatology averages, not live readings. How accurate is our data?

Warmest beaches in Thailand right now

BeachRegionSea
Freedom BeachPhuket29.7°C
Salad BeachKo Pha-ngan29.7°C
Kata BeachPhuket29.6°C
Bang Tao BeachPhuket29.6°C
Charlie BeachTrang & Satun29.6°C
Similan Island 4 BeachKo Similan29.6°C
Lipa Noi BeachKo Samui29.6°C
Khao Takiab BeachHua Hin & Cha-am29.6°C
Lonely BeachKo Chang & Trat29.6°C
Long Beach Phi PhiKrabi29.5°C
Chaweng BeachSurat Thani29.5°C
Rawai BeachPhuket29.5°C
Monkey Beach Phi PhiPhi Phi Islands29.5°C
Shark Bay Ko TaoKo Tao29.5°C
Kai Bae BeachKo Chang & Trat29.5°C
Jomtien BeachChonburi29.4°C
Lamai BeachSurat Thani29.4°C
Bophut BeachSurat Thani29.4°C
Ya Nui BeachPhuket29.4°C
White Sand Beach Ko ChangKo Chang & Trat29.4°C
Kamala BeachPhuket29.3°C
Freedom BeachPhuket29.3°C
Maya BayKrabi29.3°C
Phra Nang Cave BeachKrabi29.2°C
Nopparat Thara BeachKrabi29.2°C
Loh Dalum BayPhi Phi Islands29.2°C
Haad YuanKo Pha-ngan29.2°C
Ao PhaiKo Samet29.2°C
Tonsai BeachKrabi29.1°C
Klong Dao BeachKrabi29.1°C
Sairee BeachSurat Thani29.1°C
Surin BeachPhuket29.1°C
Kantiang BayKo Lanta29.1°C
Pattaya Beach LipeTrang & Satun29.1°C
Coconut Beach Khao LakKhao Lak29.1°C
Ao Prao Ko KoodKo Chang & Trat29.1°C
Ao Prao Ko SametKo Samet29.1°C
Railay BeachKrabi29.0°C
Karon BeachPhuket29.0°C
Laem Sing BeachPhuket29.0°C
Nui BayKo Lanta29.0°C
Emerald Cave BeachTrang & Satun29.0°C
Ko Kradan BeachTrang & Satun29.0°C
Donald Duck BayKo Similan29.0°C
Nang Thong BeachKhao Lak29.0°C
Freedom Beach Ko TaoKo Tao29.0°C
Klong Prao BeachKo Chang & Trat29.0°C
Ngamkho BeachKo Chang & Trat29.0°C
Sai Kaew BeachKo Samet29.0°C
Patong BeachPhuket28.9°C
Klong Nin BeachKo Lanta28.9°C
Sunset Beach LipeTrang & Satun28.9°C
Ao LeukKo Tao28.9°C
Ao Wong DueanKo Samet28.9°C
Bottle BeachSurat Thani28.8°C
Mai Khao BeachPhuket28.8°C
Nai Yang BeachPhuket28.8°C
Pakarang BeachKhao Lak28.8°C
Panwa BeachPhuket28.7°C
Choeng Mon BeachKo Samui28.7°C
Thong Nai Pan NoiKo Pha-ngan28.7°C
Wong Amat BeachPattaya28.7°C
Haad RinSurat Thani28.6°C
Bang Niang BeachKhao Lak28.6°C
Klong Chao BeachKo Chang & Trat28.6°C
Hua Hin BeachPrachuap Khiri Khan28.5°C
Pattaya BeachChonburi28.5°C
Kata Noi BeachPhuket28.5°C
Nai Harn BeachPhuket28.5°C
Ao Nang BeachKrabi28.5°C
Freedom Beach PhuketPhuket28.5°C
Klong Muang BeachKrabi28.5°C
Long Beach Ko LantaKo Lanta28.5°C
Klong Khong BeachKo Lanta28.5°C
Silver Beach SamuiKo Samui28.5°C
Cha-am BeachHua Hin & Cha-am28.5°C
Bamboo IslandKrabi28.4°C
Maenam BeachKo Samui28.4°C
Taling Ngam BeachKo Samui28.4°C
Tubkaek BeachKrabi28.3°C
Sunrise Beach LipeTrang & Satun28.3°C
Thong Nai Pan YaiKo Pha-ngan28.3°C

Sea temperature in Thailand — FAQ

How warm is the sea in Thailand in September?

The sea off Thailand averages about 29.0°C in September, based on long-term monthly averages for this coast.

When is the best time to swim in Thailand?

Thailand is warmest in April (around 30.0°C) and coldest in January (around 27.0°C). There are typically 12 months a year when the water sits above 22°C.

What is the average yearly sea temperature in Thailand?

Across all twelve months, the sea in Thailand averages about 28.7°C.

Do you need a wetsuit to swim in Thailand?

In peak season (around April, ~30.0°C) most swimmers are comfortable without a wetsuit. Outside summer, when the water drops toward 27.0°C, a 3/2mm to 5/4mm wetsuit is recommended.