Which Thai island? A month-by-month comparison
Thailand's two coasts have opposite wet seasons, which is the single most useful fact for choosing an island and the one most guides bury. Below: 11 islands across three coasts, each month marked dry, mixed or wet, then what each place is actually for — and what it costs and takes to get there from Bangkok.
Rain columns come from the hand-compiled monthly normals behind our weather pages, which cover 7 stations — not one per island. Each island below says which station its columns borrow and how far away it sits. Fares and journey times were checked 7 September 2026.
Which coast is dry, by month
| Islands & station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gulf of Thailand — Catches the northeast monsoon: wettest October–December, when the Andaman is drying out. The rest of the year is comparatively dry. | ||||||||||||
| Koh Samui, Koh Phangan, Koh TaoKoh Samui station | 12 | 6 | 5 | 6 | 10 | 8 | 9 | 10 | 12 | 17 | 18 | 17 |
| Andaman coast — Hit directly by the southwest monsoon: wet May–October, dry and busiest November–April. | ||||||||||||
| Phuket, Koh LipePhuket station | 6 | 4 | 6 | 10 | 19 | 18 | 17 | 19 | 21 | 20 | 13 | 9 |
| Koh Phi Phi, Krabi & Ao Nang, Koh LantaKrabi station | 5 | 4 | 6 | 9 | 18 | 17 | 16 | 18 | 20 | 19 | 12 | 8 |
| Eastern Gulf — Follows the mainland pattern — wet May–October, dry November–April — with more rain than the upper Gulf coast because Trat province is one of the wettest in Thailand. | ||||||||||||
| Koh Chang, Koh Samet, Koh KoodPattaya station | 3 | 3 | 5 | 7 | 14 | 13 | 14 | 15 | 17 | 15 | 7 | 3 |
| Driest coast | East | East | Gulf | Gulf | Gulf | Gulf | Gulf | Gulf | Gulf | East | East | East |
One row per weather station rather than one per island, because that is what the data actually is: we hold monthly normals for 7 stations and the islands share them by coast. Numbers are typical rain days in that month, not rainfall totals — a 15-rain-day month on the Gulf can still be fifteen afternoons of one-hour storms. The bottom row picks the coast with the fewest rain days averaged across its stations; in October and November that is a much narrower win than it looks.
Gulf of Thailand
Catches the northeast monsoon: wettest October–December, when the Andaman is drying out. The rest of the year is comparatively dry.
Koh Samui
Driest Feb–Aug · wettest Sep–Jan
The developed one: a ring road, hospitals, chain hotels and an airport, so it works without any planning at all.
- Diving & snorkelling
- Snorkelling is thin off the main beaches; the diving worth booking is a day trip out to Sail Rock or a transfer to Koh Tao.
- Nightlife
- Chaweng's strip runs late and loud; Bophut and Maenam are where people go to avoid it.
- With children
- The strongest of the eleven for families — shallow Choeng Mon and Bophut beaches, real hospitals, and no boat needed to arrive.
- What goes wrong
- Everything costs more because the airport is a near-monopoly, and Chaweng in high season is a resort strip rather than an island.
Getting there: from Bangkok, ฿600–฿1,100 and 10h–13h on the cheapest option we hold; ฿2,000–฿6,600 and 1h–1h20 on the quickest. All options →
Rain columns are Koh Samui's own monthly normals.
Koh Phangan
Driest Feb–Aug · wettest Sep–Jan
Two islands in one: Haad Rin's party end, and a quiet north coast with dirt-road beaches most visitors never reach.
- Diving & snorkelling
- Sail Rock — the Gulf's best-known dive site — is closer from here than from Samui, and day boats run from Thong Sala.
- Nightlife
- Full Moon dominates the calendar; the week before and after it, accommodation prices across the island move with it.
- With children
- Workable off the Haad Rin end, but the roads are steep and the north-coast beaches take a pickup to reach.
- What goes wrong
- Arriving in Full Moon week without a booking, then finding the price of everything has doubled.
Getting there: from Bangkok, ฿698–฿778 and 11h55–14h55 on the cheapest option we hold; ฿900–฿1,400 and 13h–15h on the quickest. All options →
Rain columns borrow Koh Samui's monthly normals, 27km away — we hold no station on Koh Phangan itself.
Koh Tao
Driest Feb–Aug · wettest Sep–Jan
Small, steep and built around diving — over twenty dive schools in a village you can walk across.
- Diving & snorkelling
- The reason the island exists commercially: the cheapest PADI Open Water certification in Southeast Asia, with whale sharks at Sail Rock between roughly April and September.
- Nightlife
- Sairee Beach bars, oriented around dive-school groups rather than clubs.
- With children
- Shark Bay's blacktip reef sharks and Koh Nang Yuan's sandbars are the draw; the steep pickup-truck roads are the obstacle.
- What goes wrong
- It is the hardest of the Gulf three to reach and the first to lose its boats when the sea gets up in November.
Getting there: from Bangkok, ฿850–฿1,250 and 12h–13h20 — the only routing we hold, so cheapest and quickest are the same trip. All options →
Rain columns borrow Koh Samui's monthly normals, 68km away — we hold no station on Koh Tao itself.
Andaman coast
Hit directly by the southwest monsoon: wet May–October, dry and busiest November–April.
Phuket
Driest Nov–Apr · wettest May–Oct
A province rather than a getaway: bridge to the mainland, international airport, and beaches that range from Patong to near-empty.
- Diving & snorkelling
- The launch point for Similan liveaboards (season roughly mid-October to mid-May) and day boats to Racha and Phi Phi.
- Nightlife
- Bangla Road in Patong is the loudest nightlife on this page by a distance; Kata and Nai Harn are the opposite.
- With children
- Kata, Karon and Bang Tao have the calm water and the infrastructure; Patong has neither.
- What goes wrong
- Choosing Patong because it is the name you knew, then spending the week trying to get away from it.
Getting there: from Bangkok, ฿700–฿1,400 and 12h–14h on the cheapest option we hold; ฿900–฿3,500 and 1h25–1h40 on the quickest. All options →
Rain columns are Phuket's own monthly normals.
Koh Phi Phi
Driest Nov–Apr · wettest May–Oct
No roads, one village, and a viewpoint climb that most of the island does at the same hour.
- Diving & snorkelling
- Shark Point and Bida Nok are the day-boat sites; the snorkelling straight off Long Beach is better than the ferry crowds suggest.
- Nightlife
- Tonsai's beach bars are the most concentrated party on the Andaman side.
- With children
- Day-trippable and beautiful; as a base it is loud at night and short of the quiet corners families want.
- What goes wrong
- Every ferry lands in the same small bay, so the island is at its worst exactly when you arrive.
Getting there: from Bangkok, ฿1,350–฿3,650 and 3h35–6h05 — the only routing we hold, so cheapest and quickest are the same trip. All options →
Rain columns borrow Krabi's monthly normals, 41km away — we hold no station on Koh Phi Phi itself.
Krabi & Ao Nang
Driest Nov–Apr · wettest May–Oct
Not an island — the mainland base for Railay, the four-island tour and the Phi Phi and Lanta piers, with an airport 20 minutes from Ao Nang. It is here because most island plans route through it.
- Diving & snorkelling
- The four-island tour and Hong Island run from Ao Nang; serious diving means a Phi Phi day boat.
- Nightlife
- Ao Nang's walking street; Railay is quieter and closes earlier.
- With children
- Ao Nang is flat, walkable and has the widest range of accommodation on the Andaman coast outside Phuket.
- What goes wrong
- Railay looks like a separate island and is priced like one, but the longtail is the only way on and off.
Getting there: from Bangkok, ฿628–฿828 and 12h25–16h30 on the cheapest option we hold; ฿900–฿3,200 and 1h20–1h35 on the quickest. All options →
Rain columns are Krabi's own monthly normals.
Koh Lanta
Driest Nov–Apr · wettest May–Oct
A road runs the length of it, so you can rent a scooter and pick a beach — rare among Thai islands.
- Diving & snorkelling
- Hin Daeng and Hin Muang, the deepest-water sites on the Andaman side, run from Saladan in the dry months.
- Nightlife
- Beach bars rather than clubs; the island's reputation is for going to bed early.
- With children
- Long, shallow west-coast beaches and the least traffic of the Andaman options.
- What goes wrong
- Half its ferries stop between May and October, and the island empties with them.
Getting there: from Bangkok, ฿1,150–฿3,650 and 4h05–6h50 on the cheapest option we hold; ฿1,200–฿3,900 and 3h35–6h15 on the quickest. All options →
Rain columns borrow Krabi's monthly normals, 55km away — we hold no station on Koh Lanta itself.
Koh Lipe
Driest Nov–Apr · wettest May–Oct
Three beaches and a walking street inside Tarutao marine park, 60km off the Satun coast.
- Diving & snorkelling
- Eight Mile Rock and the Tarutao park sites; visibility here is regularly the best in Thai waters.
- Nightlife
- Walking Street's bars, which is the whole of it.
- With children
- Sunrise Beach is shallow and calm; the journey to reach it is the part that rules families out.
- What goes wrong
- Getting there is the trip: 4–5.5 hours from Hat Yai, five from Phuket, and the boats only run in season.
Getting there: from Bangkok, ฿1,538–฿1,938 and 19h15–24h on the cheapest option we hold; ฿1,700–฿3,800 and 6h10–9h40 on the quickest. All options →
Rain columns borrow Phuket's monthly normals, 185km away — we hold no station on Koh Lipe itself. Lipe sits far enough south of that station for its own season to be narrower than the columns suggest: the boats run roughly November to April and most stop outside it. Read the columns as an Andaman-coast pattern, not a Lipe forecast.
Eastern Gulf
Follows the mainland pattern — wet May–October, dry November–April — with more rain than the upper Gulf coast because Trat province is one of the wettest in Thailand.
Koh Chang
Driest Nov–Apr · wettest May–Oct
Thailand's second-largest island: a mountainous, forested interior with the development strung along the west coast.
- Diving & snorkelling
- The wrecks off Koh Chang — including the HTMS Chang — are the eastern seaboard's main dive draw.
- Nightlife
- Lonely Beach at one end, near-silence at Klong Prao and Bang Bao at the other.
- With children
- Klong Prao and Kai Bae have the calm water; the steep coast road between beaches is the thing to be careful about.
- What goes wrong
- The west-coast road is genuinely steep in places, and scooter accidents on it are the island's reputation.
Getting there: from Bangkok, ฿895–฿1,250 and 6h40–8h — the only routing we hold, so cheapest and quickest are the same trip. All options →
Rain columns borrow Pattaya's monthly normals, 184km away — we hold no station on Koh Chang itself. Trat province is wetter than Pattaya through the southwest monsoon, so read the May–October columns as a floor rather than a forecast.
Koh Samet
Driest Nov–Apr · wettest May–Oct
The closest island to Bangkok that still feels like one — small enough to walk end to end.
- Diving & snorkelling
- Snorkelling off the smaller east-coast bays; no serious diving industry.
- Nightlife
- Fire shows and beach bars on Sai Kaew, quiet everywhere south of it.
- With children
- The short journey does most of the work here: 3.5–5.5 hours from Bangkok including the crossing.
- What goes wrong
- It is a national park with a per-person entry fee on arrival, and it fills with Bangkok weekenders every Saturday.
Getting there: from Bangkok, ฿350–฿700 and 3h30–5h30 — the only routing we hold, so cheapest and quickest are the same trip. All options →
Rain columns borrow Pattaya's monthly normals, 73km away — we hold no station on Koh Samet itself.
Koh Kood
Driest Nov–Apr · wettest May–Oct
The quietest island on this page: few roads, few bars, resorts spread thinly along the west coast.
- Diving & snorkelling
- Snorkelling off the fringing reefs; divers generally base on Koh Chang instead.
- Nightlife
- Effectively none, which is the point.
- With children
- Calm water and no traffic, offset by the longest journey of the three eastern islands.
- What goes wrong
- Catamarans from Laem Sok run twice a day, not hourly, and some stop entirely in the June–September low season.
Getting there: from Bangkok, ฿1,020–฿1,470 and 7h30–9h30 — the only routing we hold, so cheapest and quickest are the same trip. All options →
Rain columns borrow Pattaya's monthly normals, 229km away — we hold no station on Koh Kood itself. The same Trat-province caveat as Koh Chang applies, and more so — Koh Kood sits further south and east than our nearest station by a wide margin.
What this comparison is missing
Per-island rain records. We hold monthly normals for 7 stations, not for eleven islands. Koh Phangan and Koh Tao borrow Koh Samui's, Phi Phi and Lanta borrow Krabi's, the eastern three borrow Pattaya's and Koh Lipe borrows Phuket's from 400km-plus away. Each card says which and how far. That is a coast-level pattern, and it is honest about being one.
Accommodation prices. We do not track them, so this page does not rank islands by what a room costs. The cost figures here are transport only, computed from the same leg table the route planner uses.
Sea state. Rain days and sea state are different things. The Gulf crossings that get cancelled in November are cancelled for wind and swell, not for rain — a dry-looking month on this table can still lose you a ferry.
Three things this table deliberately leaves out have their own pages. The named beaches on each island, with what they are like and how you reach them, are on Thailand's beaches. Island-hopping speedboats, longtails and the Ang Thong marine-park tours are in boat trips & cruises. And the scooter almost everyone rents on arrival still needs a motorcycle licence plus an IDP for the insurance to pay — renting a motorbike has the fines and the road-risk figures behind that.
Frequently asked questions
Gulf or Andaman islands in October?
The Gulf, but only just — and neither is dry. In October our stations put the Andaman coast at 19.5 rain days on average against the Gulf's 17 and the eastern islands' 15. October is the month the two patterns cross over: the Andaman is coming out of its wet season while Koh Samui is going into its own, which peaks in November at 18 rain days. If the trip is fixed to October, the Andaman is improving by the week and the Gulf is getting worse by the week.
Which Thai islands are driest in December?
On the numbers, the eastern trio — Koh Chang, Koh Samet and Koh Kood sit behind our Pattaya station at 3 rain days in December, against 8.5 for the Andaman and 17 for the Gulf, where Koh Samui is still finishing its northeast monsoon at 17 rain days. Two caveats on that ranking: Trat province, where Koh Chang and Koh Kood are, is wetter than Pattaya, and the Andaman islands have the calmer seas and the fuller ferry timetable in December. The clear part is the bottom of the table — December is the wrong month for Samui, Phangan and Tao.
When is the best time for the Gulf islands?
Roughly Feb–Aug, the stretch our Koh Samui station holds below its own yearly average for rain days, with the wettest run at Sep–Jan. February and March are the two driest months on that station at 6 and 5 rain days. That is the opposite of the pattern most people expect, because the Gulf coast faces the northeast monsoon rather than the southwest one.
Which island is cheapest to reach from Bangkok?
Koh Samet, at ฿350–฿700 one way on the cheapest option we hold (3h30–5h30). At the other end, Koh Lipe costs from ฿1,538–฿1,938 and takes 19h15–24h. Fares are per adult, one way, and exclude the taxi or songthaew at either end — which on Koh Tao and Koh Lipe is a real addition, not a rounding error.
Do the island ferries stop in the rainy season?
Some of them. 9 of the 70 legs we track carry a season note: the Phuket–Koh Lipe and Koh Lanta–Koh Lipe speedboats are dry-season services, Krabi–Koh Lanta drops to a reduced timetable May–October, and the Koh Chang–Koh Kood catamarans thin out or stop in the June–September low season. The routes that keep running all year are the short mainland crossings — Donsak to Samui and Phangan, Chumphon to Koh Tao — and the Phi Phi ferries from Phuket and Krabi.
Which Thai island is best for diving?
Koh Tao for learning and Koh Lipe for visibility. Koh Tao has over twenty dive schools in one village and the cheapest PADI Open Water certification in Southeast Asia, with whale sharks at Sail Rock roughly April to September. Koh Lipe sits inside Tarutao marine park and regularly has the clearest water in Thailand, but the arrival is 4–5.5 hours from Hat Yai and the boats only run November to April. Phuket is the base for Similan liveaboards, whose own season runs roughly mid-October to mid-May.
Which Thai island suits families with young children?
Koh Samui, Koh Lanta and Koh Samet, for three different reasons: Samui has an airport, hospitals and shallow beaches at Choeng Mon and Bophut, so no boat is needed at all; Koh Lanta has a road down its spine and the least traffic on the Andaman side; Koh Samet is 3h30–5h30 from Bangkok including the crossing, the shortest island journey on this page. Koh Lipe and Koh Kood have the calmest water and the longest journeys — in July's rain those journeys are the deciding factor.
Is July a bad month for Thai islands?
Not everywhere. July averages 9 rain days on our Gulf station against 16.5 on the Andaman side — the Gulf sits in a dry pocket between its two monsoon seasons in June and July, which is why Samui, Phangan and Tao work in the European summer while Phuket and Krabi are at their wettest. Andaman rain in July usually falls as afternoon storms rather than all-day rain, but the seas are rougher and some small-island boats pause.
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