Vitamin D in Thailand: best months for sun and a travel guide

The best months for vitamin D in Thailand are December to March. In February, a full dose of about 1,000 IU takes around 6 minutes at midday for skin type III at age 30, with 8.2 usable sun hours a day. For a beach stay it is too hot from April to May and rainy or stormy from June to November.

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Thailand month by month

Thailand is rated at its median coastal place, for skin type III at age 30. Click a month for the details.

Month	Rating	Sun window	Peak UV	Full dose, age 30	Full dose, age 65	Afternoon high	Rainy days
January	Excellent	7.2 h	7.3	7 min	14 min	32°C	6/30
February	Excellent	8.2 h	8.6	6 min	12 min	33°C	8/30
March	Excellent	8.3 h	8.7	6 min	11 min	32°C	12/30
April	Too hot	8.7 h	9.0	6 min	11 min	32°C	14/30
May	Too hot	7.7 h	8.1	7 min	12 min	34°C	20/30
June	Bad weather	7.2 h	7.4	7 min	14 min	31°C	19/30
July	Bad weather	6.5 h	7.0	8 min	14 min	30°C	25/30
August	Bad weather	7.9 h	7.9	7 min	13 min	30°C	25/30
September	Bad weather	6.5 h	7.5	7 min	13 min	30°C	27/30
October	Bad weather	7.1 h	7.5	7 min	13 min	29°C	25/30
November	Bad weather	6.5 h	7.1	8 min	14 min	29°C	28/30
December	Good	5.9 h	6.0	9 min	17 min	28°C	16/30

Sun window is the number of hours a day with UV Index 2.5 or higher. Full dose is the minutes at midday for about 1,000 IU of vitamin D with a quarter of the body bare, for skin type III. Rainy days are days with at least 1 mm out of 30.

Travel guide: why go to Thailand

Why go

Thailand offers warm sea, friendly service, great food and good prices, with islands for every style from party beaches to quiet coves.

Best for

Backpackers, couples, families, divers and long-stay winter visitors.

What to expect

A hot dry season from November to February on both coasts, and monsoon rain from May to October on the Andaman side (Phuket, Krabi). The Gulf side (Samui) is driest in the first months of the year. March to May is very hot.

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Places in Thailand

Each place has its own climate, so its best months can differ from the country as a whole.

Bangkok best: Excellent

Huge, hot, energetic capital of temples, street food and malls.

Best for city lovers, foodies

Best months November to March · Avoid too hot from April to May; rainy or stormy from June to October

Thailand's bustling, frenetic capital, known among the Thai as Krung Thep

Phuket best: Excellent

Thailand's biggest island with beaches, nightlife and boat trips.

Best for families, couples, groups

Best months January to March, June · Avoid too hot from April to May; rainy or stormy from July to December

The original Thai paradise island, now very developed but with some still beautiful beaches

Krabi best: Excellent

Limestone cliffs, islands and emerald water on the Andaman coast.

Best for couples, climbers, families

Best months January · Avoid too hot from February to May; rainy or stormy from June to December

Ao Nang best: Excellent

Main beach resort of Krabi, a base for island boat trips.

Best for families, couples

Best months January to April, June · Avoid rainy or stormy in May and from July to December

Ko Phi Phi best: Excellent

Postcard islands with limestone cliffs and busy day trips.

Best for couples, divers, party travellers

Best months January to March, June · Avoid too hot in April; rainy or stormy in May and from July to December

Ko Lanta best: Excellent

Relaxed long-beach island with a gentle pace.

Best for families, couples, backpackers

Best months June, December to April · Avoid rainy or stormy in May and from July to November

Khao Lak best: Excellent

Quiet palm-lined beaches and a base for the Similan Islands.

Best for divers, couples, families

Best months February · Avoid too hot from March to May; rainy or stormy from June to January

Ko Samui best: Excellent

Gulf island with a mix of luxury resorts and budget bungalows.

Best for couples, families, honeymooners

Best months February, March, June, December · Avoid too hot from April to May; rainy or stormy in January and from July to November

Comfortable, nature, and entertainment hippie mecca gone upmarket

Ko Pha Ngan best: Excellent

Home of the Full Moon Party, plus quiet coves.

Best for backpackers, party groups, yogis

Best months February, March, June, December · Avoid too hot from April to May; rainy or stormy in January and from July to November

Site of the famous Full Moon Party with miles of quiet coastline

Ko Tao best: Excellent

Cheap diving courses and clear water.

Best for divers, backpackers

Best months December to May · Avoid rainy or stormy from June to November

Pattaya best: Excellent

Big, loud resort city close to Bangkok.

Best for groups, short stays

Best months August, November to March · Avoid too hot from April to May; rainy or stormy from June to July and from September to October

One of the main tourist destinations, known for its wild nightlife

Hua Hin best: Excellent

Royal-favoured beach town with a long sandy shore.

Best for families, retirees, golfers

Best months November to February · Avoid too hot from March to May and in August; rainy or stormy from June to July and from September to October

Ko Chang best: Excellent

Green mountainous island near the Cambodian border.

Best for families, hikers, budget travellers

Best months November to January · Avoid too hot from April to May; rainy or stormy from February to March and from June to October

Once a quiet island, now undergoing major tourism development

Ko Samet best: Excellent

Small island with soft white sand, a short trip from Bangkok.

Best for weekenders, couples, families

Best months November to April · Avoid rainy or stormy from May to October

The nearest island beach escape from Bangkok

Ko Lipe best: Excellent

Tiny southern island with clear water and a backpacker vibe.

Best for snorkellers, couples, backpackers

Best months July, December to March · Avoid rainy or stormy from April to June and from August to November

Small island in the middle of Tarutao National Park, with great reefs and beaches

Chiang Mai best: Excellent (inland)

Northern city of temples, markets and hill treks.

Best for culture travellers, digital nomads

Best months October to February · Avoid too hot from March to May; rainy or stormy from June to September

De facto capital of Northern Thailand and the heart of Lanna culture

Ayutthaya best: Excellent (inland)

Ruined ancient capital north of Bangkok.

Best for history fans, day-trippers

Best months November to January · Avoid too hot from February to June and in August; rainy or stormy in July and from September to October

A historical city, UNESCO World Heritage Site and old capital of Siam (full name is Phra Nakhon Si Ayutthaya)

Railay Beach best: Excellent

Cliff-backed peninsula reachable only by boat, loved by rock climbers.

Best for climbers, couples

Best months January · Avoid too hot from February to May; rainy or stormy from June to December

Some short descriptions come from Wikivoyage (CC BY-SA 4.0).

Questions about vitamin D in Thailand

When is the best time to visit Thailand for vitamin D?

Can you get vitamin D from the sun in Thailand in December?

Yes, but slowly. In December a full dose takes about 9 minutes at midday for skin type III at age 30, with 5.9 usable hours a day.

How long do I need in the sun in Thailand?

In February, the best month, about 6 minutes at midday with a quarter of the body bare, for skin type III at age 30; about 12 minutes at age 65. Darker skin needs longer and fair skin burns sooner, so keep sessions short. This is an estimate for planning, not medical advice.

Which months should I avoid in Thailand?

For a beach stay, avoid the months when it is too hot from April to May and rainy or stormy from June to November.

What is the best place in Thailand for vitamin D?

In February the strongest sun of the places we rate is around Ko Lipe. Each place has its own rating, so open the place list to compare them.