Best Time to Visit Thailand: Month, Region and Island Decision Table

Pick the coast first. The Andaman side is wettest from August to October, the Gulf side from October to December. Similan and Surin close from 16 May to 14 October. Chiang Mai has haze on 18.7 to 26.8 days a month from January to March. Songkran 2027 runs 13 to 15 April.

By Vincent Nguyen and team

The Andaman coast is wettest from August to October, when Phuket gets 308.7, 350.4 and 336.0 mm. The Gulf coast is wettest from October to December, when Koh Samui gets 294.9, 444.6 and 263.1 mm.

The Andaman Sea lies on the west side of the south and the Gulf of Thailand on the east side. This page picks the month for your goal. For rain totals month by month, read Thailand weather by month and region.

Best month by goal

Rain figures are mean monthly rain from one Thai Meteorological Department station per coast.

Andaman or Gulf: which coast in which month

The southwest monsoon covers Thailand from mid-May to mid-October and brings heavy rain along the coasts. The northeast monsoon runs from about mid-October to mid-February.

Heavy rain in the south continues until December, and the east side gets more of it than the west side. That puts the Gulf under the heaviest rain in November.

Compare the two stations in the months where the choice flips:

• February: Phuket gets 24.0 mm and Koh Samui 64.3 mm.
• August: Koh Samui gets 102.2 mm and Phuket 308.7 mm.
• November: Phuket gets 178.2 mm and Koh Samui 444.6 mm.

October is wet on both coasts, with 336.0 mm at Phuket and 294.9 mm at Koh Samui. The west coast covers Ranong, Phang Nga, Phuket, Krabi, Trang and Satun. Chumphon and Surat Thani are on the east coast.

The driest stretch of the upper east coast of the south sits behind the Tenasserim range, in Phetchaburi and Prachuap Khiri Khan. See the Hua Hin guide for that stretch. Bases: Phuket and Koh Samui.

Island closures by date

A good rain month can still be a closed month for the island you want. The list runs in calendar order.

• 16 May: Similan Islands tourism closes until 14 October. The Surin Islands close from 16 May to 14 October as well.
• 1 June: Koh Rok closes until 30 September. Tarutao closes Adang, Rawi and other listed islands from 1 June to 30 September.
• 1 June: Hat Chao Mai closes Koh Cheuk and Koh Waen until 30 September.
• 1 July: Koh Samet closes Koh Kudi until 15 August, then Koh Talu from 16 August to 30 September.
• 1 August: Maya Bay, Loh Samah and Lo Ko bay close until 30 September. Phang Nga Bay closes Koh Lawa Yai, Ao Khian and Koh Boi Yai until 30 September.
• 1 August: Koh Ha and Hin Muang-Daeng close until 30 September.
• 1 November: Mu Ko Ang Thong national park in the Gulf closes sites until 15 December.

The Similan Islands park opened for the season on 15 October 2026. The Andaman marine parks, including Similan, Surin, Phi Phi, Lanta and Phang Nga Bay, have opened. Opening of some sites can change with the weather.

During the Maya Bay closure the rest of the Phi Phi park stays open. Phi Phi is best from November to April, with milder weather and less frequent rain.

Month-by-month detail is on Best Thai Islands by Month. Entry rates are on Thailand national park fees. The Phi Phi page is the Maya Bay guide.

Bangkok and temples

Bangkok gets 11.6 mm of rain in December and 21.4 mm in February. It gets 335.9 mm in September and 288.7 mm in October. Heat peaks in April, with a mean daily maximum of 35.7 °C.

Plan temple days for December if you want the driest month. In April, start early or book shaded stops, since April is the hottest month.

Songkran adds three bank holidays from 13 to 15 April. The Bangkok guide and Bangkok in 3 days have entry prices and hours for the temples.

The north and the haze season

Chiang Mai records haze on 18.7 days in January, 22.1 in February, 26.8 in March and 17.1 in April. Haze days fall to 1.5 in May and 0.0 in June. November has 7.8 haze days.

The cool season runs from mid-October to mid-February. Chiang Mai rain peaks in August at 223.3 mm and falls to 40.9 mm in November.

Chiang Mai province banned open burning in all areas until 31 May 2026. In 2025 the provincial police described the ban as running from 1 January to 15 May. Burning that causes a nuisance carries up to 3 months in jail or a fine of up to THB 25,000, or both (as of January 2025).

The Chiang Mai guide and the Pai guide cover the north in detail.

Festivals, holidays and alcohol-ban days

Dates that move a plan, in the order they fall:

• Songkran is a public holiday of 3 days, 13 to 15 April. In 2027 that is Tuesday 13 to Thursday 15 April. Read the Songkran dates and rules page for water-gun and alcohol rules.
• Sky lanterns for Loy Krathong in Chiang Mai are notified from 24 November 2026 at 0300 UTC to 25 November 2026 at 1800 UTC. The evening windows run 19:00 to 01:00 Thai time.
• Lantern release is banned in the air-navigation safety zone around Chiang Mai airport. The penalty there is up to THB 200,000, or up to 5 years in prison, or both (as of November 2024). See Loy Krathong and Yi Peng.
• The Full Moon Party is held at Haad Rin on the night of every full moon. See the Full Moon Party guide.

Nobody may sell alcohol on Makha Bucha, Visakha Bucha, Asarnha Bucha and the first and last days of Buddhist Lent. In 2027 Makha Bucha falls on Sunday 21 February, with Monday 22 February as the bank holiday in its place.

Visakha Bucha is Thursday 20 May 2027. Asarnha Bucha is Sunday 18 July, and Monday 19 July is the bank holiday in its place. Alcohol otherwise sells from 11:00 to 24:00. The full calendar is on Thailand public holidays and alcohol ban days.

Peak weeks and wet-month risks

Around Christmas and New Year, book your room in advance. In low season, visitors can expect discounted room rates.

People have drowned in strong riptides, especially during monsoon season. Jellyfish come close to shore, particularly in the rainy season from May to October. Read jellyfish and rip currents at Thai beaches before a wet-month beach trip.

Dates that move

The start and end of the two monsoons can vary from the normal dates in any year. The start of the rainy season can come 1 to 2 weeks early or late. Leave slack at both ends of a window.

The closure dates above come from the 2026 announcement, so check the park notice for your sailing date. For a first trip, start with the first-time in Thailand checklist and the Thailand islands guide. The other trip-planning pages are in the planning hub.

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Not confirmed: The Loy Krathong and Yi Peng dates for next year are not notified yet; check the Chiang Mai lantern notice before you book. Rain figures come from one station per coast, so a beach elsewhere on that coast gets different rain.

Prices, timetables and opening hours change; check with the operator before you travel. See how guides are checked.

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