November to February
Cool and dry
The easy season
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Best time to visit Koh Larn: months, rain and sea conditions
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Book a seatMonth-by-month temperatures and rainfall from the nearest weather station, what TAT and the Thai Meteorological Department say about the seasons, and how the sea and the boats behave in each.
Editorial team, kohlarntour.click · Updated November 12, 2026 · A 7 min read
Summary view
- Best seasonTAT picks the cool season, November to February, as the best travel window.1
- Driest monthFebruary is the driest month at the Sattahip station, with 11 mm of rain.2
- Hottest spellThe Thai Meteorological Department calls April the most sweltering month.3
- Rainy seasonTAT sets the rainy season between May and October.4
- Calm seaThe city report rates Sangwarn highest for calm water in December to April.5
The short answer by season
If you want a single answer to the best time to visit Koh Larn, take the cool season. TAT's own pick is November to February, when humidity is lower.1 The Sattahip weather station agrees on the rain: December records 16 mm and February just 11 mm, with 1 day of at least 2.5 mm in each month.2,2 That station lies 33.8 km from the island.6 Those are the months when a day trip is least likely to lose its boat to the weather.
The city report adds a sea-side clue. It rates Sangwarn Beach highest between December and April, when the calm sea suits coral viewing.5 That window overlaps the cool season and extends it into the hot weeks of March and April, which suits visitors who care more about clear water than about a cool breeze.
Everything outside those months is a trade. The wetter months bring more rain, a livelier sea and a bigger chance of a cancelled activity. A trip to Koh Larn in the rainy season can still be good, but treat it as a day with a plan B instead of a promise. The rest of this page puts figures behind each of those trades.
Month by month at the island
Koh Larn weather figures here come from the Sattahip station, 33.8 km away, and not from the island itself, so read them as the regional pattern.6 In January the average daily high is 32.6 °C and 22 mm of rain falls in the month,2 while February has a high of 32.7 °C and only 11 mm.2 March warms to 33.2 °C and 46 mm of rain.2 The heat builds slowly, and the sea stays warm throughout.
April brings a high of 34.2 °C and 90 mm of rain,2 and May reaches 34.3 °C with 154 mm.2 This is the turn from the dry half of the year to the wet half, and it is gradual rather than sudden. June and July add 170 mm and 163 mm respectively, with highs of 33.6 °C and 33.2 °C.2,2 August records 126 mm of rain, a lower figure than its neighbours, so a mid-season gap is possible, though it is not something to bank on.2
The wettest stretch is September and October. The station records 258 mm in September and 283 mm in October, with 13 and 14 wet days of at least 2.5 mm.2,2 Then the pattern turns: November is down to 67 mm with a high of 33.4 °C, and December is down to 16 mm.2,2 The speed of that drop is why the cool season is a clear favourite, not a vague one.
Month by month
Koh Larn temperatures and rain through the year
- Jan12.6 h
- Feb12.3 h
- Mar12.0 h
- Apr11.6 h
- May11.3 h
- Jun11.1 h
- Jul11.2 h
- Aug11.4 h
- Sep11.8 h
- Oct12.1 h
- Nov12.5 h
- Dec12.6 h
Mid-month hours with no sun, and days when precipitation reaches 2.5 mm or above. Source: NOAA, station Sattahip (temperatures and rainfall, all 12 months), 1991 to 2020.2
The wet months and the sea
For TAT the rainy season runs from May until October.4 The Thai Meteorological Department sees rain building and temperatures easing from late May, and names September as the month of heaviest rainfall across most of the country.7,8 Our Sattahip station peaks one month later, in October, which is a reminder that the national picture and the local one do not match to the week.
Rain is only half the story for a boat trip. TAT tells swimmers to take particular care off coastal areas in the monsoon season and to obey red flags,9 and it warns that jellyfish can come close to the shore, especially in the rainy season.10 The city report adds that people move from Tawaen to Tian Beach when the monsoon season arrives, so the side of the island you use changes with the wind.12
Tour operators build the weather into their terms. One operator states that boats can fail to leave in some seasons even once you stand at the pier, and then offers a substitute program in town. Another says that parasailing requires good weather and that water activities depend on it. Read the cancellation and weather clauses before you book a wet-season date. The rhythm of Koh Larn tourism follows these seasons, so plan around them.
Choose your month
Which month fits your trip?
Match your priorities to the season the sources describe, then check the forecast for the week.
If I want the safest weather
November to February
TAT names it the best time to travel.1
If I want calm water for corals
December to April
The city report says the sea is calm at Sangwarn.5
If I can handle heat for clear days
March to May
April is the hottest month nationally.3
If I accept a gamble on rain
May to October
This is the rainy season by TAT's definition.4
If I want the least rain
February
The driest month at the Sattahip station.2
If I want an event in the evening
Late November
The fireworks festival lights up the bay.11
Seasons compared
Cool, hot or wet?
March to May
Hot
Heat before the rains
See the trips
May to October
Rainy
Greener, wetter, rougher
See the tripsThe hot weeks and the sun
The hot spell comes before the rains. In the Thai Meteorological Department's words April is the hottest month of the year,3 and our station agrees with a high of 34.2 °C that month and 34.3 °C in May.2,2 On a boat with little shade and a beach with little cover, that heat is the main enemy, more than the rain that follows, and it is why early starts and shade breaks matter.
Pattaya's sun is very strong in TAT's description, and it wants lotion put on liberally and often.14 For a reef the right lotion is mineral, such as zinc oxide, backed by a hat and long sleeves so you use less.13 A rash vest does more work than a bottle of lotion in the hot weeks, and a wide hat does more again.
Daylight is long all year. Daylight runs from 11.4 hours at mid-month in January to 12.9 in June, according to the station's monthly facts.2,2 That means a day trip has time at any season, though the hot middle of the day is best spent in water or shade. Aim for beach time early and late, and use the midday window for lunch and a rest.
Plan the date
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The year in order
How the seasons follow each other
November
The cool season begins
TAT's best travel window opens in November.1
December
Dry and calm
The station records 16 mm of rain in the month.2
April
The hottest month
The Thai Meteorological Department calls it the most sweltering.3
Late May
The rains return
The second half of May is the start of the rainy season.7
September
The heaviest rain nationally
The Thai Meteorological Department reports the most abundant monthly rainfall.8
October
The station peak
Sattahip records 283 mm, its wettest month.2
Weekends, holidays and events
We found no official visitor count by month or by weekday for Koh Larn, so this page does not claim a quiet day. What the sources do show is a lively calendar around Pattaya. The Pattaya International Fireworks Festival is held in late November and lights up Pattaya Bay,11 and Pattaya celebrates Songkran as the Wan Lai festival in April, a week later than the rest of the country.16
The island sits inside that calendar. TAT has listed an event on Ko Lan on 30 March 2024 at Samae Beach,17 and a beachfront music festival with a stop on Ko Larn on 20 to 21 March 2026.18 Both fall in the dry, hot part of the year. Check the TAT calendar for your own dates, because a festival stop can fill the beach it uses and change the mood of the island for a day.
TAT calls Pattaya a year-round destination,19 which tallies with a practical point: the sources name no month in which the island closes, only months in which the weather and the crowd differ. If you travel on a public holiday or a weekend, book the earliest boat you can, and expect the pier to be busy rather than empty.
Video
Best time to visit Pattaya
Travel 2 Where on YouTube · Tap play to load the video; not before.
Take particular care when swimming off coastal areas, especially during the monsoon season
Time of day on the island
When you arrive matters nearly as much as the month, and the structure of the tour decides it for you. Our Bangkok day trip spends 2.5 hours on the road and 30 minutes on a speedboat before 3.5 hours on Ko Lan. A trip with that shape reaches the island in the middle of the day, so shade and water are worth more to you than a perfect sunrise.
A Pattaya-based trip changes the clock. A Pattaya departure lists 4 hours of sightseeing, swimming and snorkeling once a drive of 1 hour and a 30 minute briefing at Bali Hai Pier are done. Starting from Pattaya rather than Bangkok gives you more time at the water, which counts for more in the hot weeks than in the cool season, when the sun is gentler.
Pick the earliest departure you can in the hot and wet months. An early start also leaves room to change plans if the day turns. That is general advice, not an official rule, so put your questions about wind, cancellations and refunds to the operator before you pay.
What to pack for the month you pick
All year, pack for sun and sea, whatever the forecast says. Sunscreen, a hat, water shoes, a dry bag and a little cash cover the basics, and TAT's advice on coral-friendly sunscreen is the right standard for a reef island.13 In the cool season add a light layer for the morning boat, since the sea breeze is cooler than the shore.
In the hot weeks, bring more water than seems sensible and plan shade breaks, since a day on a beach with little cover can drain you. In the rainy months, bring a light rain jacket, a waterproof bag for phones and a change of clothes, and keep the day flexible. A listing in our set recommends a change of clothes and a waterproof bag for personal items on a water sports trip.
Finally, make a decision rule for the day: if the red flag is up, or the crew says no, treat the beach as a place to have lunch and wait. TAT's advice is to obey warning signs, red flags above all, and to swim only on approved beaches.9 A safe day with a missed activity is better than a bad one, and the island is not going anywhere.
FAQ
Common questions, answered fast.
What is the best month to visit Koh Larn?
When does the rainy season start?
Which month is the wettest?
Is April too hot for the island?
Are boats cancelled in bad weather?
They can be.
A listing says boats may not depart even after you reach the pier in certain seasons, and offers an alternative program in Pattaya city.
Is the sea calm in the cool season?
The city report says so for Sangwarn.
The report rates Sangwarn highest in December to April for calm water.5
Are there jellyfish in the rainy season?
They can come near the shore.
TAT says jellyfish may drift close to shore, mainly when it rains.10
Sources
- Tourism Authority of Thailand (TAT Newsroom) · Thailand’s comfortable, cooler months of November-February are a fantastic time to travel ↩
- NOAA · Global Summary of the Month, Station Sattahip (temperatures and rainfall, all 12 months) (NOAA GHCN TH000048477 (Sattahip)), 1991 to 2020 ↩
- Thai Meteorological Department · 3-month Climate Prediction of Thailand, April - June 2022 (PDF, climate-0199) ↩
- Tourism Authority of Thailand (TAT Newsroom) · Marine safety measures and regulations in Thailand ↩
- Pattaya City · Pattaya City Yearly Report 2018 (English translation, PDF, Research and Evaluation Section) ↩
- NOAA · Global Summary of the Month, station TH000048477 Sattahip, 1991 to 2020 ↩
- Thai Meteorological Department · 3-month Climate Prediction of Thailand, April - June 2022 (PDF, climate-0199) ↩
- Thai Meteorological Department · 3-month Climate Prediction of Thailand, September - November 2022 (PDF, climate-0215) ↩
- Tourism Authority of Thailand (TAT Newsroom) · Marine safety measures and regulations in Thailand ↩
- Tourism Authority of Thailand (TAT Newsroom) · Marine safety measures and regulations in Thailand ↩
- Tourism Authority of Thailand (TAT Newsroom) · Rediscovering many different facets of Pattaya and more ↩
- Pattaya City · Pattaya City Yearly Report 2018 (English translation, PDF, Research and Evaluation Section) ↩
- Tourism Authority of Thailand (TAT Newsroom) · Make sure your sunscreen is not on the banned list in Thailand ↩
- Tourism Authority of Thailand · Pattaya: destination page (Wayback Machine copy of tourismthailand.org) ↩
- Tourism Authority of Thailand (TAT Newsroom) · Marine safety measures and regulations in Thailand ↩
- Tourism Authority of Thailand (TAT Newsroom) · Rediscovering many different facets of Pattaya and more ↩
- Tourism Authority of Thailand (TAT Newsroom) · March 2024's festivals and events in Thailand ↩
- Tourism Authority of Thailand (TAT Newsroom) · March 2026 Festivals and Events in Thailand ↩
- Tourism Authority of Thailand (TAT Newsroom) · Rediscovering many different facets of Pattaya and more ↩