Thailand in March

When the Gulf turns to glass

March is the pivot from cool season to hot season. Temperatures climb into the low-to-mid 30s, the midday sun gets serious, and the air stills. What that stillness does to the Gulf of Thailand is the month's great reward: the sea flattens out, warms up, and clears — around Koh Tao, March into April brings some of the best diving visibility of the year.

Calm clear water at Haad Yao beach, Koh Phangan

It also marks a change of rhythm. The European high-season crowds start to drain away just as conditions in the water peak, so beaches at Ban Krut, on Samui's quieter coasts and around the islands feel more spacious than in January or February. The one place March does not flatter is the far north, where the agricultural burning season fills the air with haze.

Transport

Tickets & connections

Search tickets on 12go

Affiliate link. If you book through it we earn a commission, at no extra cost to you.

Tours

Tours & activities

See tours on GetYourGuide →

At a glance

Hot season begins — expect low to mid 30s and strong sun
Gulf seas are at their calmest; superb diving visibility around Koh Tao
High-season crowds thin as the heat builds
Burning-season haze affects the far north — beach months, not mountain months

Good to know

Treat the midday sun with respect — plan active things for early morning and late afternoon.
Booking a dive course on Koh Tao? March visibility is excellent; reserve schools a little ahead.
Skip the far north this month — burning-season haze makes it the worst time for Chiang Mai.
The Gulf's calm seas make March ideal for island-hopping — ferry crossings from Chumphon are at their gentlest.

Coast by coast: where the weather is best

Gulf coast: this is its moment. Ban Krut, Hua Hin and Chumphon are hot, dry and calm — mornings are golden, and the swimming is as good as it gets. Out on the islands, Koh Samui and Koh Phangan bask in settled weather while Koh Tao's dive sites hit peak visibility; whale sharks are spotted more often around now.

The Andaman coast is also hot and mostly dry, though its season is winding towards the April–May turn. Bangkok is hot but functional — plan sights for mornings and shopping malls for afternoons. The far north is the exception: burning-season haze around Chiang Mai and Pai can be severe in March, so this is not the month for northern trekking or viewpoints.

Long quiet Gulf coast beach in the March heat

What to do and where to go in March

Get in the water. March is the classic month for a Koh Tao dive course, for snorkelling day trips, and for lazy swimming everywhere on the Gulf. On the mainland coast, shape the day around the sun: sunrise walks and bike rides at Ban Krut, a long shaded lunch, then back to the beach late afternoon when the light softens.

Where to go: choose coast over mountains. The Gulf side — Hua Hin, Ban Krut, Chumphon and the islands — combines the calmest water with the thinnest crowds, and ferry crossings to Koh Tao are at their smoothest. Skip Chiang Mai and the far north this month unless you must, and check air-quality forecasts if you do.

Thai fruit stall piled with tropical fruit

Frequently asked questions

How hot is Thailand in March?

Hot. Expect low to mid 30s across the country, with strong sun and rising humidity. Coastal spots on the Gulf get a sea breeze that takes the edge off — the interior and cities feel hotter.

Is March a good month for the Gulf islands?

One of the best. Seas around Koh Samui, Koh Phangan and Koh Tao are calm and clear, ferry rides are smooth, and diving visibility at Koh Tao is near its yearly peak.

Should I avoid northern Thailand in March?

For outdoor plans, yes. March is the heart of the burning season, and haze around Chiang Mai and the far north can reach unhealthy levels. Save the mountains for November to early February.

Does it rain in Thailand in March?

Rarely. March is one of the driest months on both coasts. The occasional build-up shower can arrive late in the month, but rain will not shape your trip.

Thailand in March

When the Gulf turns to glass

Tickets & connections

Tours & activities