Islands are chosen by two things: the month you travel and how many days you are ready to spend getting there. Thailand has two seas, and the rains reach them from different monsoons: the Andaman Sea is wet from May to October, and the Gulf of Thailand in the south from October to January. Below are nine of the most searched islands with their season from Thai Meteorological Department (TMD) normals, national park fees and closures as of 19 October 2026.
Islands in one table
| Island | Sea | National park and fee for foreigners | Driest by TMD | Closures and season | More |
|---|---|---|---|---|---|
| Phuket | Andaman | Sirinat National Park in the northwest, 200 baht | December-March, Phuket station | rain and waves on the west from May to October | Phuket, islands around |
| Ko Lanta (Krabi) | Andaman | Mu Ko Lanta 200 baht, Ko Rok, Ko Ngai and Ko Ha 400 baht | December-March, Ko Lanta station | Ko Rok closed from 16 May to 15 November | Ko Lanta |
| Phi Phi (Krabi) | Andaman | Phi Phi Don, Phi Phi Leh and Bamboo 400 baht | by DNP driest in February, most rain in July | Maya Bay closed from 1 August to 30 September | Phi Phi |
| Samui | Gulf of Thailand | Samui is not in the DNP fee table, nearby Ang Thong 200-300 baht | February and April, and 102-134 mm in May-September | peak rain in November, Ang Thong takes visitors from 16 December to 30 October | Samui |
| Phangan | Gulf of Thailand | Than Sadet-Ko Pha-ngan 100 baht | as on Samui, nearest station Ko Samui | peak rain in November | Phangan |
| Tao | Gulf of Thailand | not in the DNP fee table | January, February and April, Chumphon station | peak rain in November, 258.6 mm | Ko Tao and Nang Yuan |
| Koh Chang | Gulf of Thailand, east | Mu Ko Chang 200 baht | November-February, mainland Trad station | very wet summer, 1,024.1 mm in July | more below |
| Koh Samet | Gulf of Thailand, east | Khao Laem Ya-Mu Ko Samet 200 baht, 300 baht at Ko Thalu, Ko Kudi, Ko Kham and Ko Khruai | November-April, Rayong station | by DNP strong waves on about 15 days a month from May to September | Koh Samet |
| Koh Larn (Pattaya) | Gulf of Thailand, east | part of Pattaya city, not in the DNP table, no fee | November-April, Phatthaya station | not a national park, boats depend on the weather | Koh Larn |
Fees are from the DNP table (revision of 2 June 2023), and the child fee is half the adult one. We call a month dry if TMD’s 1991-2020 normals show under 100 mm of rain: that threshold is ours, TMD has no such definition. For Koh Chang the station is on the mainland, for Phangan and Tao the nearest stations are on Samui and in Chumphon, and for Phi Phi we use the DNP park’s own figures.
The Andaman Sea: Phuket, Lanta, Phi Phi
This is the side of the southwest monsoon: TMD describes it as blowing from May to October and bringing rain and waves to exposed coasts. By normals, the Phuket station gets 24-82 mm a month from December to March and the Ko Lanta station 24.1-69.0 mm. For Phuket by month see when to go to Phuket.
Phuket. According to DNP, Koh Chang is the third largest island in the country after Phuket and Samui, which means Phuket and Samui are the biggest. Beaches by area and season are in which Phuket beach to choose, and nearby islands in Phuket islands. The Similans are closed from 16 May to 14 October, and boats run from Tap Lamu pier, about 70 km, departing at 08:30 and returning at 15:00 according to DNP. They are open now: Similan Islands.
Ko Lanta. An island in Krabi province, with Mu Ko Lanta National Park. The fee is 200 baht, and 400 baht for Ko Rok, Ko Ngai, Ko Ha and the Hin Daeng and Hin Muang rocks. Ko Rok is closed from 16 May to 15 November, and in the DNP list of 19.10.2026 the Zone 2 houses and the campsite on Ko Rok are closed from 31.03.2025. The road, the beaches and the season: Ko Lanta.
Phi Phi. Hat Noppharat Thara-Mu Ko Phi Phi National Park, Krabi. By the park’s data it gets about 2,231 mm a year, most in July and least in February. Maya Bay is closed every year from 1 August to 30 September, and in 2026, according to Time Out Bangkok, it reopened on 1 October. On 19.10.2026 DNP keeps closed diving on the west side of Ko Kai and at Ko Yung. A trip from Phuket: Phi Phi in a day.
The Gulf of Thailand, south: Samui, Phangan, Tao
The seasons are shifted here: by TMD the south on the Gulf gets its heaviest rain in the northeast monsoon. The Ko Samui station records 64-134 mm a month from February to September and 295, 445 and 263 mm in October-December. By TMD’s 2026-2027 forecast, from Chumphon southwards there is heavy rain and waves of 2-4 m from mid-October to early January.
Samui. The TMD station stands on the island itself. Nearby is Ang Thong Marine Park: by its DNP page it takes visitors from 16 December to 30 October, the park’s own best time is February-August, the fee is 200 baht and 300 baht on Ko Wua Talap and Ko Mae Ko. Details: Samui and Ang Thong from Samui.
Phangan. Than Sadet-Ko Pha-ngan National Park, fee 100 baht. There is no TMD station on the island, and Samui is the reference. What and where: Phangan.
Tao. An island north of Samui, not in the DNP fee table. The nearest TMD stations are Samui and Chumphon: Chumphon is driest in January, February and April (51.7-96.7 mm) and gets 258.6 mm in November. A day on Tao and neighbouring Nang Yuan: Ko Tao and Nang Yuan from Samui.
Getting between the islands: Raja Ferry boats run to the company’s timetable, Donsak to Samui every hour from 05:00 to 19:00 in about 1 h 30 min, Donsak to Phangan (Thong Sala) about 2 h 30 min, Samui to Phangan about 1 h 30 min. Lomprayah catamarans link Samui, Phangan and Tao several times a day, with times and prices on the 2026 timetable. There is no direct ferry between Phuket and Samui: see from Phuket to Samui.
The Gulf of Thailand, east: Koh Chang, Koh Samet, Koh Larn
Koh Chang. Trat province. According to DNP the park covers more than 40 islands, Koh Chang itself is 8 km from Laem Ngop, about 30 km long and 14 km wide, and boats take about 40 minutes and leave every hour. The rainy season runs from May to October, with about 4,700 mm a year. At the mainland Trat station it is dry from November to February (27.8-85.2 mm) and July gets 1,024.1 mm. The fee is 200 baht. On 19.10.2026 DNP keeps closed the islands of Ko Thong Lang, Ko Kra and Ko Thian and diving at Ko Yak Yai. We do not have a Koh Chang page yet.
Koh Samet. An island in a national park, fee 200 baht and 300 baht at the islets of Ko Thalu, Ko Kudi, Ko Kham and Ko Khruai. Boats from the Ban Phe piers take about 30 minutes, from 6:00 to 17:00. By the park page there are strong waves on about 15 days a month from May to September, and storms occur from December to March too. On 19.10.2026 there are no DNP closures. In detail: Koh Samet from Pattaya.
Koh Larn. The island closest to Pattaya, 8.4 km in a straight line from Bali Hai pier to Na Ban pier. It belongs to Pattaya city and is not in the DNP table, so there is no national park fee. Boats and beaches: Koh Larn from Pattaya.
What is open and closed on 19 October 2026
From the DNP park status list and park pages:
- The Similans are open from 15 October, some dive sites are closed
- Ko Rok is closed until 15 November
- Surin: not in the closure list, and by the park page the closure starts on 16 May
- Koh Chang: Ko Thong Lang, Ko Kra, Ko Thian and diving at Ko Yak Yai are closed
- Phi Phi: diving on the west side of Ko Kai and at Ko Yung is closed, Maya Bay is open according to press
- Ang Thong, Than Sadet-Ko Pha-ngan, Koh Samet: no restrictions in the list, and Ang Thong by its page takes visitors until 30 October
Dates on park pages are standing dates, and DNP can open or close a park by separate announcement, so check the status list on the DNP portal before booking: it is in Thai.
How to choose an island
- December-March and a marine park. The Similans or Ko Rok from Lanta: the Similan season starts on 15 October and Ko Rok’s on 16 November, both until 15 May
- Few days and no wish to sail. Koh Larn from Pattaya, half a day with no national park fee
- Summer, sea without rain every day. Samui, Phangan and Tao: 102-134 mm a month from May to September
- November-February in the east. Koh Samet, Koh Larn and Koh Chang
- Just a beach with no transfers. One island with a beach and an airport nearby: Phuket or Samui
Who the Gulf does not suit: those going to Samui, Phangan or Tao in November-December, the wettest months of the year. Who the Andaman Sea does not suit in summer: those who want to swim on the west beaches of Phuket and Lanta without waves and red flags.
What is not on this page
We have not yet checked Ko Lipe, Ko Kood, Ko Mak and Ko Si Chang against primary sources and do not describe them. Islands near Phuket that we do cover: Ko Yao Noi and Ko Yao Yai, Racha, Coral Island and Khai. We found no sea water temperature normals in primary sources.
FAQ
Which Thai islands are best in winter?
From December to March by TMD normals it is driest on the Andaman Sea: Phuket, Lanta, Phi Phi. On the Gulf of Thailand it is drier from November on Koh Samet, Koh Larn and Koh Chang. Samui, Phangan and Tao are in peak rain in November-December: 444.6 and 263.1 mm at the Samui station.
Which island should you choose from May to October?
Samui, Phangan and Tao: the Samui station records 102-134 mm of rain a month from May to September, against 237-350 mm in Phuket. But from October the rains gather strength there (294.9 mm), and Koh Chang is very wet in summer, up to 1,024 mm in July at the Trat station. The Similans, Surin and Ko Rok are closed in these months.
Do you have to pay to enter the islands?
If an island or part of it is in a national park, yes. By the DNP table a foreigner pays from 100 baht on Phangan to 500 baht at the Similans and Surin. Koh Larn is not in the table, so there is no national park fee there. The table dates from 2 June 2023, we found no newer revision on the DNP portal, and the child fee is half the adult one.
Which islands are closed in the rainy season?
The Similans are closed from 16 May to 14 October, Ko Rok from 16 May to 15 November, Maya Bay on Phi Phi from 1 August to 30 September, and Surin's closure starts on 16 May. By its DNP page, Ang Thong takes visitors from 16 December to 30 October, so it is closed from 31 October to 15 December.
How do you get from Samui to Phangan and Tao?
Lomprayah catamarans run between the islands on the 2026 timetable, and Raja Ferry carries passengers and vehicles: Samui to Phangan about 1 h 30 min, Donsak to Samui about 1 h 30 min every hour from 05:00 to 19:00. For catamaran prices and times see the Lomprayah timetable, and we break them down on our Samui and Phangan pages.
Sources
- DNP. National park entrance fees for individuals (dataset, revision of 2 June 2023)
- DNP. Opening and closing status of national parks
- DNP. Mu Ko Similan National Park
- DNP. Mu Ko Surin National Park
- DNP. Mu Ko Lanta National Park (Ko Rok)
- DNP. Hat Noppharat Thara-Mu Ko Phi Phi National Park
- DNP. Mu Ko Ang Thong National Park
- DNP. Than Sadet-Ko Pha-ngan National Park
- DNP. Mu Ko Chang National Park
- DNP. Khao Laem Ya-Mu Ko Samet National Park
- TMD. Climatological Data of Thailand for 30 Year Period (1991-2020), stations Phuket, Ko Lanta, Ko Samui, Chumphon, Trad, Rayong, Phatthaya
- TMD. Cool season forecast 2026-2027, issued 9 October 2026
- Raja Ferry. Donsak-Samui-Phangan timetable
- Lomprayah. Timetable 2026
- Government Public Relations Department (PRD). Maya Bay and nearby areas closed until 30 September 2024 (7 August 2024)
- Time Out Bangkok. Maya Bay reopens October 1 after annual closure (29 September 2026), press
- OpenStreetMap. Na Ban pier on Koh Larn (node 1228583305), Bali Hai pier in Pattaya
Found an error or outdated fact? Tell the editors, we will fix it and update the check date.