The west coast faces the sunset every evening the sky is clear.
Koh Tao travel guide
Koh Tao is a year-round island, but the seasons shape the water, the diving and the sky. Here is what each part of the year is really like — and when to come for calm seas, clear water, quiet, or those west-coast sunsets.
The west coast faces the sunset every evening the sky is clear.
The quick answer: February to April is the driest and sunniest with the best water for diving, but it is also busiest. The shoulder months of May, June and September are quieter with mostly lovely weather, while late October to December is the rainier monsoon window.
Koh Tao sits in the Gulf of Thailand, so its weather runs on a different clock to the Andaman coast (Phuket, Krabi). When the west coast of Thailand is wet, the Gulf is often dry — and Koh Tao's rain arrives later in the year.
| Season | Months | What to expect |
|---|---|---|
| Dry & sunny | Jan – Apr | Least rain, calm seas, clear water. Peak season, busiest. |
| Warm shoulder | May – Sep | Hot, mostly dry, occasional short showers. Quieter, good value. |
| Monsoon | Oct – Dec | Wettest, especially November. Greener island, rougher seas. |
This is the classic time to visit. Skies are clear, the sea is calm, and underwater visibility is at its best. It is also peak season, so the island is livelier and villas book up well ahead — if you want these months, plan early. March and April are hot and gorgeous, and among the better windows for spotting whale sharks.
A lovely, under-rated stretch. Days are hot and mostly dry, with the odd short tropical shower that clears quickly. There are fewer people, prices soften, and the dive sites are calmer. September in particular is a favourite of ours — green, quiet, and often a strong month for whale-shark sightings.
The northeast monsoon brings Koh Tao's wettest weather, peaking in November. Expect heavier rain, rougher seas and the occasional ferry cancellation on the windiest days. It is not a washout — the rain usually comes in short bursts, the island is lush and green, and you will have beaches almost to yourself — but it is the one window where we will be candid about the weather when you ask.
Diving runs all year on Koh Tao, but the water is clearest in the dry months, roughly March to June, when visibility often reaches 15–25 metres. Quieter months also mean smaller groups on the dive sites. If you are learning to dive with our partners at Dive Onda, any month works — the training is in sheltered water — but the dry season gives the prettiest conditions.
Whale sharks are the highlight for many divers. They can turn up any time, but sightings cluster around March–April and September–October when plankton blooms draw them in. Wildlife is never guaranteed, but Koh Tao is one of Thailand's more reliable spots.
Because LUM faces west over the sea, every clear evening is a sunset. The dry season gives the most consistently clear skies; the shoulder months can deliver the most dramatic colour as clouds catch the last light. For the quietest, most private feel, aim for May–June or September, then settle in on the hillside and watch the sky change from your private pool.
February to April is the sweet spot: the driest, sunniest weather, calm seas and the clearest water for diving and snorkelling. It is also peak season, so it is busier and villas book up early. May, June and September are quieter shoulder months with mostly good weather and the odd short shower.
Koh Tao sits in the Gulf of Thailand, so its wettest window is the northeast monsoon from late October to December. November is the rainiest month and can bring rougher seas and the occasional ferry disruption. The rain usually comes in short heavy bursts rather than all day, and the island is at its greenest.
Whale sharks can appear off Koh Tao at any time of year, but sightings are most common around March to April and again around September to October, when plankton blooms draw them in. Nothing is guaranteed with wildlife, but Koh Tao is one of the more reliable places in Thailand to see them.
Underwater visibility is generally best in the dry months from around March to June, when the water is calm and clear, often 15 to 25 metres. It can drop after heavy rain and during the November monsoon. Diving runs year-round, and quieter months mean smaller groups on the dive sites.
Koh Tao's west coast faces the sunset all year, so there is a sea-facing sunset every evening the sky is clear. The dry months from January to April give the most consistently clear skies, while the shoulder months can bring dramatic colour as clouds catch the light. From a west-coast hillside like LUM's, you see it straight over the water.
Tell us your rough dates and we will be honest about the weather, the sea and the crowds — then help you plan around the best of it. Book direct with the owners; no agents, no OTA fees.