Koh Lanta sits on the Andaman coast, so its dry season (November-April) and green season (May-October) run opposite to the Gulf islands like Koh Samui and Koh Phangan. What makes Koh Lanta genuinely different, though, is how seriously the island treats its low season -- a real share of restaurants, bars and guesthouses close outright, not just quiet streets. Here's what each month means for weather, closures and everyday life.
Koh Lanta sits on Thailand's Andaman coast, so it runs on the same dry-season calendar as Phuket and Krabi rather than the Gulf islands: a long dry season from November to April (peak season, calm seas, minimal rain) and a green season from May to October, driven by the southwest monsoon. Long-run averages put October as the wettest month by rainfall (around 330mm) and February as the driest (around 30mm). What genuinely sets Koh Lanta apart from bigger islands is that a real share of its beachside restaurants, bars and guesthouses close outright for part of the wettest stretch, most commonly August and September -- a documented commercial pattern, not just quieter streets. For live rents by area, use the BAANLYY Koh Lanta hub.
Temperatures move modestly across the year; rainfall, sea state and which businesses are open change far more. Months marked ★ are dry-season favourites.
| Month | Season | Typical temp | Rain & sea | Verdict |
|---|---|---|---|---|
| January | Dry, peak season | 25-33°C | Minimal rain, calm seas, sunny | ★ Excellent — peak high season, everything open |
| February | Driest | 25-34°C | Driest month (~30mm), calm and clear | ★ Excellent — the driest month of the year |
| March | Dry, warming | 26-34°C | Dry, calm, warming toward the hot season | ★ Great — still reliably dry |
| April | Hot, dry (ending) | 27-34°C | Hot, mostly dry, Songkran, seas still calm | Good but hot; last full month before the switch |
| May | Green season begins | 26-33°C | Showers increasing, some businesses start winding down | Transitional — shoulder month, thinner crowds |
| June | Wet, monsoon starts | 26-31°C | Westerly monsoon brings spells of rain, occasional storms | Low season — rain builds, first closures begin |
| July | Wet | 26-31°C | Regular showers, usually short-lived rather than all-day | Low season — quiet, wet, cheap |
| August | Wet, heavy spells | 27-31°C | Heavy downpours mixed with sunny breaks, high humidity | Low season — many beachside businesses closed |
| September | Very wet | 26-30°C | Among the wettest months on record, frequent storms | Low season — most closures in effect |
| October | Wettest on record | 26-30°C | Heaviest rainfall of the year in most long-run averages (~330mm) | Low season — wettest month; some businesses stay shut |
| November | Season reopening | 25-31°C | Rain easing through the month, seas calming | Improving — resorts and restaurants reopening for the season |
| December | Dry, peak season | 25-32°C | Dry, sunny, calm — high season in full swing | ★ Excellent — festive peak season |
Guide figures compiled from long-run climate averages; actual weather and business closures vary year to year.
This is the section that sets Koh Lanta apart from most other BAANLYY weather guides -- the low season here has a real, visible commercial impact, not just fewer tourists on the beach.
Unlike a mainland city or even Phuket, Koh Lanta is a small, seasonal-tourism-dependent island, and a meaningful share of its beachside restaurants, bars and independently run guesthouses close outright for one to several months during the wettest stretch -- typically somewhere in the June-October window, most commonly August and September. This is a genuine operational pattern, not just quieter streets: owners often travel, do renovations, or simply find it uneconomical to stay open through the lowest-demand weeks.
Larger hotels, dive operators, hospitals, pharmacies, banks, 7-Elevens and most restaurants in the main towns (Ban Saladan, Old Town, Klong Dao) generally stay open year-round, since they serve the resident and long-stay population as well as tourists. It is the smaller, most tourist-dependent beachfront businesses -- particularly on quieter beaches -- that are most likely to close.
If you're moving to or visiting Koh Lanta in the June-October window, don't assume every restaurant, dive shop or beach bar you researched online will actually be open -- call or message ahead, especially outside the main towns. On the upside, this is also when rents and short-term deals are softest, and the island is at its quietest and greenest.
The dry season (Nov-Apr) is Koh Lanta's high season: calm seas, sunny skies and daytime highs of 25-34°C, with February the driest month and December-February the busiest. The green season (May-Oct) arrives with the southwest monsoon: showers build through May and June, become heavier and more frequent through July and August, and peak somewhere in the September-October window depending on the year -- long-run averages point to October as the single wettest month. Rain typically comes as spells rather than all-day downpours, and November sees conditions steadily improve as the island reopens for the season. This is the opposite timing to Koh Samui and Koh Phangan in the Gulf of Thailand, which are wettest later, around October-November.
For the most reliable weather and the widest choice of open restaurants and beach bars, target November-April, especially December-February. For lower prices, thinner crowds and a genuinely quieter island, the green season (May-October) delivers real value -- just confirm ahead that the specific place you want to eat, dive or stay is actually open, particularly in August and September.
| When | What to pack |
|---|---|
| Year-round | Light, breathable clothing, reef-safe sunscreen, a hat and good sandals -- Koh Lanta is warm and humid every month. |
| Dry season (Nov-Apr) | Book accommodation, ferries and dive trips ahead of the November-April peak, especially over December-February when the island is busiest and driest. |
| Green season (May-Oct) | Pack a compact rain shell or umbrella and a dry bag for boat transfers, and check ahead before relying on a specific restaurant, dive shop or beach bar being open -- especially August through October, when closures are most common. |
Koh Lanta is long and relatively narrow, so most beaches share similar monsoon exposure during the wet season -- but the main towns of Ban Saladan and Old Town keep more shops, clinics, banks and restaurants open year-round than the quieter southern beaches, which lean more heavily on seasonal tourism. If you're relocating for the long term or staying through the green season, choosing a base closer to one of the main towns means more reliable access to everyday amenities when smaller beachside businesses close. Explore the trade-offs on the Koh Lanta hub.
November through April is Koh Lanta's dry season and the classic best time to visit -- calm Andaman seas, minimal rain and every business open, with January and February the driest and most popular months. The trade-off is peak-season pricing and crowds. If you don't mind rain and want lower prices and a quieter island, the May-October green season offers real value, though be aware that many beachside businesses close during the wettest stretch, typically August through October.
The wet, or 'green', season runs roughly May to October, driven by the southwest monsoon off the Andaman coast. Long-run averages point to October as the single wettest month on record (around 330mm of rain), though September is also cited as a peak-rainfall month in some data sets -- either way, expect the heaviest, most frequent rain somewhere in the June-October window. February is the driest month, averaging only around 30mm.
Yes, genuinely -- this is a real, documented pattern on Koh Lanta rather than just quieter streets. A meaningful share of independently run beachside restaurants, bars and small guesthouses close outright for part of the June-October wet season, most commonly in August and September, when demand is lowest. Larger hotels, dive operators and businesses in the main towns (Ban Saladan, Old Town, Klong Dao) generally stay open year-round. If you're visiting or relocating in this window, confirm ahead rather than assuming a specific spot is open.
Koh Lanta sits on Thailand's Andaman (west) coast, while Koh Samui and Koh Phangan sit in the Gulf of Thailand (east coast). The two coasts are driven by opposite monsoon systems: Koh Lanta's wet season runs with the southwest monsoon roughly May to October, peaking around September-October, while the Gulf islands' wet season arrives later with the northeast monsoon, peaking around October-November. This is the same Andaman-versus-Gulf pattern that separates Phuket from Koh Samui.
Somewhat. The island is long and relatively narrow, so most beaches face the same westerly monsoon exposure during the wet season, but the main towns (Ban Saladan, Old Town) sit more inland/sheltered and keep more amenities open year-round than the quieter southern beaches. Because so many small businesses close in the wettest months, choosing an area near Ban Saladan or Old Town gives more reliable access to shops, clinics and restaurants if you're staying through the green season. Monsoon-season rents are typically softer, so relocating in the wet months can save money.
Primary and official sources are cited above. Government rules, fees and procedures in Thailand change over time and vary by office; always confirm current requirements with the relevant authority before relying on them. BAANLYY never takes paid placement in editorial content.
Whether you come for the dry-season high or the green-season value, match the right Koh Lanta area and home to how you want to live.
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