What stays open on Koh Lanta during the rainy season

Low season on Koh Lanta is not a shutdown. The island gets greener, quieter and wetter, the west-coast sea turns rough, and a short list of things genuinely closes. This guide sets out what changes from May to October, using climate normals for the island’s own weather station and the 2026 park schedules, checked on 18 October 2026.

Rain falling May–Oct

about 79% of the year

Wettest month

August, 342 mm

Most rainy days

October, about 18

Car ferry

runs all year

The Koh Lanta rainy season in brief

The rainy season runs roughly from May to October, when the southwest monsoon blows in from the Andaman Sea. The UK Foreign Office gives the same months for Thailand’s rainy season. On Koh Lanta that means three changes: showers and some longer wet spells, rough water on the west-coast beaches that face the monsoon wind, and seasonal closures of the offshore park islands.

What does not change: the car ferry and roads, supermarkets, pharmacies, many hotels and restaurants, taxis and laundry. That is the green-season trade: fewer visitors and a greener island, in exchange for fewer dependable sea days.

Rainfall by month on Koh Lanta

The best long-term record is the Ko Lanta station itself (WMO 48566), in the World Meteorological Organization’s 1991–2020 climate normals. These are 30-year averages, not a forecast.

Month	Average rainfall	Days with 1 mm or more	Average high
February (driest)	24 mm	1.8	33.5°C
May	228 mm	14.2	32.6°C
June	286 mm	15.1	31.9°C
July	289 mm	14.9	31.6°C
August	342 mm	14.8	31.2°C
September	319 mm	17.0	30.9°C
October	298 mm	17.9	31.0°C
November	148 mm	12.3	31.3°C

Two things stand out. Even in the wettest months, about half the days have less than 1 mm of rain, so a typical week mixes showers with usable hours. And October, when the parks are scheduled to reopen, is still one of the wettest months, with the most rainy days of the year.

The averages hide spells. When the monsoon strengthens, the Thai Meteorological Department issues wind-wave advisories for the Andaman Sea. Its advisory of 31 May 2026 gave waves of about 2 m from Krabi southwards. In July 2026 it forecast 2 to 3 m in the lower Andaman Sea from 10 to 15 July and told small boats to stay ashore. Those are the days when small boats stay in and plans move ashore.

Sea conditions on the west coast in the low season

Treat the west-coast sea as unsafe for swimming until the flags and lifeguards say otherwise. The beaches from Khlong Dao (Klong Dao) to Khlong Nin (Klong Nin) and the south face the southwest wind, which brings surf and currents. The UK Foreign Office warns that people have drowned in strong riptides in Thailand, especially in the monsoon season. It also says jellyfish can come close to shore from May to October.

• Never swim at a red flag, and ask your hotel about the beach that morning.
• Do not swim alone, after drinking, or in strong onshore wind.
• If a current pulls you out, swim parallel to the beach, not against it.
• Wear shoes on the sand after storms and do not touch stranded jellyfish.

That last point is not theoretical. On 11 June 2026, Mu Ko Lanta National Park temporarily closed Laem Tanod, Koh Haa and Koh Ngai after Portuguese man o’ war washed ashore, Nation Thailand reported, and reopened them on 13 June.

National park closures in the Koh Lanta green season

The park islands close on staggered schedules, and the dates are set each year. TAT’s notice of 15 January 2026 says closures depend on weather and park conditions, so a scheduled date is not a promise.

1. Jan Open
2. Feb Open
3. Mar Open
4. Apr Open
5. May Open, weather allowing
6. Jun Koh Rok, Chuak, Waen closed
7. Jul Koh Rok, Chuak, Waen closed
8. Aug Most islands closed
9. Sep All listed closed
10. Oct Due to reopen
11. Nov Open
12. Dec Open

Department of National Parks 2026 status sheet linked by TAT: Koh Rok, Koh Chuak and Koh Waen 1 Jun–30 Sep; Koh Haa, Koh Mook, Koh Kradan and Maya Bay 1 Aug–30 Sep; the Emerald Cave 1–30 Sep. Maya Bay’s reopening on 1 October was reported; for the other sites, 1 October is the scheduled reopening. All dates depend on weather and park conditions.

Place	2026 closure	Status
Koh Rok	1 Jun–30 Sep	Official 2026 schedule
Koh Chuak, Koh Waen	1 Jun–30 Sep	Official 2026 schedule
Koh Haa	1 Aug–30 Sep	Official 2026 schedule
Koh Mook, Koh Kradan	1 Aug–30 Sep	Official 2026 schedule
Emerald Cave	1–30 Sep	Official 2026 schedule
Maya Bay, Phi Phi	1 Aug–30 Sep, reopened 1 Oct	Official schedule; reopening reported by The Thaiger
Smaller Mu Ko Lanta islands	16 May–14 Oct	Thai National Parks, general wording (June 2026)

Sources disagree on the edges: Thai National Parks’ general wording is wider than the 2026 list. A past year’s schedule shows a pattern, not next year’s dates, and the 2027 schedule is likely to appear around December. For Koh Rok and Koh Haa in depth, read when Koh Rok and Koh Haa are open.

What is open on Koh Lanta in low season

Almost everything on land, and the sheltered water on the east side. This is the practical picture as checked on 18 October 2026.

Activity	May to October	What to do instead
Koh Rok and Koh Haa snorkelling	Closed in the park windows above	Book from October, with a spare date
Phi Phi and other sea trips	Weather decides each day	Keep a back-up land day
Tung Yee Peng mangroves	Inside sheltered channels; tide and conditions decide	Ask about the tide on your date
Koh Talabeng sea caves	Cave access depends on tide and sea	Ask the day before
Old Town, viewpoints, waterfalls	Open	Skip waterfalls after heavy rain
National park headquarters	Listed 08:30–16:30 daily (June 2026)	Check for park notices
Taxis, laundry, shops	Daily	Use a covered vehicle in rain
Car ferry to the mainland	All year	Allow for rain on the drive

On the water, the east coast is the low-season option. The Tung Yee Peng mangroves sit on Koh Lanta’s east side, away from the open swell that hits the west-coast beaches. We arrange kayaking at Tung Yee Peng and Koh Talabeng, and the tide shapes each trip. The article on mangrove or sea cave kayaking helps you choose between them.

On land, a sightseeing tour by car covers Lanta Old Town, the beaches and the national park. You can shorten it if a storm rolls in. Two cautions. The park headquarters area at Laem Tanod closed for two days in June 2026 and reopened on 13 June, so check for park notices before you go. And the Foreign Office notes that caves and waterfalls are at risk of flash floods after heavy rain.

For getting around, a covered Koh Lanta taxi is easier than a scooter on wet roads. The article on getting around without a scooter compares the options. And clothes take longer to dry in the humid months, which is when our laundry service earns its place.

Do businesses close in the Koh Lanta low season?

Some do, many do not, and no one publishes a count. Guides that quote percentages disagree widely, so we do not repeat them. A digital nomad guide published on 14 October 2026 says many restaurants cut hours or close, and some beach shacks at Khlong Khong and Khlong Nin shut for the whole wet season. One coworking space, KoHub, says on its own site that it opens from 1 November to 30 April and closes for the low season.

For boats, Bundhaya Speed Boat’s route list (18 October 2026) showed Koh Lanta to Phi Phi and to Phuket as all year. Its routes south to Koh Mook, Koh Ngai, Koh Kradan and Koh Lipe ran from about mid-October to 20 May. The car ferry from Ban Hua Hin pier runs all year.

Koh Lanta in June and in September

June is the gentler end. Koh Rok closes on 1 June, but in 2026 Koh Haa was scheduled to stay open until 31 July. It still closed for two days from 11 June over Portuguese man o’ war, which shows how far conditions decide. An average June has about 15 rainy days.

September is the heart of the closures, with Koh Rok, Koh Haa and Maya Bay all scheduled shut in 2026, and the second-highest rainfall of the year. Plan it around land days and the mangroves, and move any reef trip to October or later.

How to book flexibly in the rainy season

• Book sea trips for early in your stay and keep a spare date.
• Check TMD wind-wave advisories the evening before.
• Choose hotel rates you can change, and confirm the hotel restaurant is open.
• Keep one land plan ready for each day you hoped to be on a boat.
• Decide on the morning, once you have seen the sky and the latest advisory.

Our shop on Highway 4245, in front of Rawi Warin Resort & Spa, is open daily from 6 am to 9 pm, so you can change a plan in person.

What to send us for a low-season plan

Message us with your dates, your hotel or area, the number of adults and children, and what you most want to do: mangroves, sea caves, Old Town, the national park or a boat trip if the weather allows. We will tell you what is running on your dates, the options and the price, and suggest a back-up for a wet day.