Best months to visit
JanuaryFebruaryDecember
December to April is the classic Koh Tao window — diving at peak visibility, calm sea, dry weather. February and March are the most reliable months. May-September brings monsoon shoulder weather (often pleasant, occasional storms). October-November is the wet season — many divers wait it out elsewhere.
Best for
Beach
December-April — Sairee Beach and Mae Haad calm and warm (sea 28-31 °C); reliable sun.
Hiking
January-March — John Suwan viewpoint, Mango Bay trail and the steep ridges are coolest and driest.
Sightseeing
December-April — snorkelling and dive trips to Shark Bay, Hin Wong and Koh Nang Yuan operate at maximum reliability with best underwater visibility.
Climate notes
- Late-year wet season (October-November): the NE monsoon dumps 280-310 mm of rain in October and November — the wettest months of the year. Rough Gulf seas can briefly suspend ferry connections.
- Long dry-warm window (December-April): January-March averages just 5-10 rainy days/month and 20-85 mm rain; sea is glassy and visibility excellent for diving.
- SW monsoon shoulder (May-September): 140-200 mm/month — the Gulf side gets less than the Andaman, but afternoon thunderstorms are routine. Diving operates throughout but visibility drops.
- Sea-temperature peak: Gulf of Thailand water hits 30-31 °C in April-May — among the warmest dive water in the world. Whale shark season at Chumphon Pinnacle peaks April-June.
- Cyclone-rare: at 10°N Koh Tao sits below typical typhoon tracks; rare tropical disturbances can cause 1-2 day disruptions in October-November.
- Steep granite headlands: Koh Tao's terrain creates micro-shelter — leeward bays stay calm even in modest weather, useful for choosing dive sites in marginal conditions.
Temperature (min / max °C)
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Regional notes
- Mae Haad and Sairee (west coast): main settlement, calm during NE monsoon (October-November) shelter behind the island; choppier in SW monsoon (May-September). Dive school core.
- Tanote Bay and Hin Wong (east): sheltered from SW monsoon swells; better in mid-year and rougher in October-November.
- Koh Nang Yuan (offshore islet to the NW): three-island viewpoint; day-trip access from Koh Tao year-round, weather permitting.
- Chumphon Pinnacle (offshore reef NW): premier dive site; whale-shark sightings April-September. Visibility best in calm weeks.
- Sail Rock (between Tao and Pha Ngan): year-round dive site, often included in two-day trips from Koh Tao.
Frequently asked questions
When is the best time to visit Koh Tao?
December to April — the dry season. February and March give the calmest sea, lowest rain, and best diving conditions. April adds whale shark sightings at peak frequency. December-January is busiest with festive crowds; March quieter with the same weather.
When is whale shark season at Koh Tao?
March-September, with peak April-June. Chumphon Pinnacle (off the NW of the island) is the main aggregation site. Sightings are not guaranteed but several encounters per week are typical in peak season.
Andaman vs Gulf of Thailand — when does Koh Tao have rain?
Koh Tao is on the Gulf side, so wet season is October-November (peak). Andaman islands (Phuket, Phi Phi, Koh Lanta) have OPPOSITE timing — wet May-October. If you want sun in October, the Andaman is past peak monsoon and the Gulf is ABOUT to enter its peak — choose carefully.
Does Koh Tao close in low season?
Less so than the Andaman islands. Most dive schools and budget resorts run year-round; some smaller bays scale back operations in October-November. Mae Haad and Sairee always have full services.
Can I dive year-round at Koh Tao?
Yes. Visibility ranges from 30+ m in dry season to 5-10 m in October-November storms. Dive schools adapt site choice to weather; the leeward east coast is dive-able even in NE monsoon. Open Water and Advanced courses run all year.
Is Koh Tao good for beginners or only experienced divers?
Both. Koh Tao is one of the world's busiest beginner-dive destinations (around 50,000 certifications a year) thanks to calm bays, low cost and shore-access training sites. Advanced divers go for whale sharks, deeper sites and tech courses.
What is the water temperature at Koh Tao?
28-31 °C year-round. April-May is the warmest at 31 °C. Many divers wear a 3 mm shorty for longer dives; most snorkellers go without a wetsuit.
Are there typhoons at Koh Tao?
Direct typhoon hits are historically rare — Koh Tao at 10°N sits below the main typhoon belt. Rare tropical disturbances recurving across the Gulf can cause 1-2 day disruptions in October-November (Tropical Storm Pabuk in January 2019 was a notable exception).
Climate data: Open-Meteo · 2020–2025