Thailand by season: when to visit Bangkok, the islands and the north

The short answer on timing

Thailand does not have one rainy season, it has several, and they depend on where you are. The country sits between the south-west monsoon, which brings rain from the Indian Ocean from about May or June to October, and the north-east monsoon, which soaks the Gulf coast later in the year. So the honest answer to "when should I go?" is a pair of questions: which month, and which coast?

For most first trips, November to February is the safest window. It is the cool, dry season, so Bangkok is bearable, the north has clear mornings, and the Andaman Sea side (Phuket, Krabi, Khao Lak) is calm. The trade-off is crowds, which build from late November and peak around the Christmas and New Year weeks.

Thailand's three seasons

• Cool and dry (about November to February). Lower humidity and clear skies. Evenings in the far north and on high ground can feel properly cool, so bring a light layer.
• Hot (about March to May). Bangkok and the central plains turn very hot and humid, and in the north the burning of fields and forest often leaves a haze that can last for weeks in the spring. Air quality can be poor around Chiang Mai at that time.
• Rainy (about May or June to October). Most days are a mix of sun and heavy showers. Everything is green and the sights are quieter, but low-lying parts of Bangkok can flood after heavy rain.

Treat the edges of each season as soft. Monsoon onset moves from year to year, so check the Thai Meteorological Department forecast in the weeks before you fly rather than relying on a fixed date.

Month by month

Which coast? Andaman versus the Gulf

This is where most mistakes happen. The Andaman coast (Phuket, Krabi, Koh Lanta, the Phi Phi islands, Khao Lak) has its best weather from about November to April and its roughest seas from May to October. Some marine national parks, including the Similan Islands, close for part of the wet season, so confirm opening dates with the national parks authority.

The Gulf coast (Koh Samui, Koh Phangan, Koh Tao) works the other way round. It is usually driest and calmest in the first half of the year and gets its heaviest rain at the end of the year. A trip in December can mean a perfect Phuket and a grey Koh Samui, so pick one side rather than trying to cover both on a short holiday.

If you like the idea of a tropical island but want to compare monsoon patterns, our guides to Boracay and Sri Lanka explain a similar split between seasons and coasts.

Bangkok and the north

Bangkok is hot all year, so the useful question is how to enjoy it. November to February lets you walk between the Grand Palace, riverside temples and markets without the worst of the heat; in the hot months, plan for early starts, a midday break indoors and evenings out. During the rains, carry a light waterproof and allow extra time to cross the city.

Chiang Mai and the northern hills are at their best from November to February: clear air, cooler mornings and green rice country after the rains. Avoid the spring haze if you are sensitive to air quality, and check local air-quality reports before you commit to dates. For the old capitals, Ayutthaya and Sukhothai are both UNESCO World Heritage sites and are mostly outdoors, so our guide on how to plan a World Heritage site visit applies: start early, cover up for temple visits and leave time for shade.

A 12-day route that follows the weather

1. Days 1–3: Bangkok. Temples, the river and markets. Use the first day to recover from the flight.
2. Days 4–5: Ayutthaya or Sukhothai. An early start for the ruins, back in Bangkok or on to the north by train or a short flight.
3. Days 6–8: Chiang Mai and the hills. Old town temples, a day in the countryside, and an ethical visit to an elephant sanctuary if wildlife is on your list; ask how the animals are cared for before you book.
4. Days 9–12: one island coast. Fly south and choose the Andaman side from November to April, or the Gulf side from about January to September.

Thailand rewards a slower pace. Add a night rather than another stop, particularly in the hot or wet months. You can sketch the route in our trip planner and compare months with the best time to visit planner.

If you are travelling from India

Several Indian cities have direct flights to Bangkok, and some also fly to Phuket and Chiang Mai, but schedules change by season, so check current timetables. Entry rules, visa exemptions and arrival formalities for Indian passport holders have changed several times in recent years. Do not rely on a blog, including this one: check the official Thailand e-Visa portal and your airline for what applies on your travel date. Vegetarian food is easy to find, but tell restaurants clearly, because fish sauce and shrimp paste are common in sauces and curries.

Practical tips

• Dress for temples. Shoulders and knees covered, shoes off at the door.
• Heat and sun. Drink often, wear a hat and use sun protection even on cloudy days.
• Sea safety. Obey red-flag warnings in the wet season; rip currents are a real danger on open beaches.
• Insurance and health. Consider travel insurance that covers medical care and any scooter riding, and ask your doctor about routine vaccines and mosquito protection.
• Pack for the month. Build a checklist with our packing list builder.

Responsible travel

Do not touch or stand on coral, keep a respectful distance from wildlife, and carry a refillable bottle where you can. Follow the rules posted at national parks, and dress and behave respectfully around temples and images of the monarchy, which are protected by law. For current advice on entry, safety and local rules, start with the Tourism Authority of Thailand and your own government's travel advisory.

Official sources

• Tourism Authority of Thailand (national tourism board)
• Thai Meteorological Department (forecasts and warnings)
• Department of National Parks, Wildlife and Plant Conservation
• Thailand e-Visa (official government portal)

Frequently asked questions