Thailand's beaches lie on two seas, and their rainy seasons fall at different times of year. The Andaman Sea coast (Phuket, Krabi, Phi Phi, Koh Lanta, Khao Lak) is driest from December to March and wettest from August to October. Koh Samui, in the Gulf of Thailand, is drier from February to September and wettest from October to December. If you choose the coast that matches your travel dates, you can find a good beach in most months of the year.
The rainfall and temperature figures below are 1991–2020 averages from Thai Meteorological Department (TMD) stations, published by the World Meteorological Organization. They are averages, not forecasts. Park dates and fees were checked in September 2026; confirm them with the park or your tour operator before you book.
Understanding Thailand's Two Coasts
Andaman Sea (West Coast)
This coast includes Phuket, Krabi (Ao Nang and Railay), Phi Phi, Koh Lanta, Khao Lak and the Similan Islands. The figures below are for Phuket.
- Driest months: December to March. February is the driest month, with about 24 mm of rain and only about 2 rain days.
- Wettest months: August to October. September averages about 350 mm of rain, and October has about 19 rain days.
- Temperature: warm all year. The average daily high stays between 31.8 °C and 34.4 °C (highest in March), and the average low stays between 24.9 °C and 26.3 °C.
Gulf of Thailand: Koh Samui and the Nearby Islands
The figures below are for Koh Samui. This article gives no figures for the nearby islands of Koh Phangan and Koh Tao, so check their forecasts before you go.
- Drier stretch: February to September. February averages about 64 mm of rain and about 4 rain days.
- Wettest months: October to December. November is the wettest month, with about 445 mm of rain.
- January: still fairly wet, with about 127 mm of rain. The dry weather starts later here than in Phuket.
- Temperature: the average daily high rises from 29.0 °C in January to 32.9 °C in May. Average humidity is between 78% and 86%.
For 2026, TMD forecasts that rain on the Gulf side of southern Thailand (Samui, Nakhon Si Thammarat and Songkhla) will continue until December. In late November 2025, rain from Cyclone Senyar flooded southern Thailand, and Songkhla (Hat Yai) was declared a disaster zone. If you visit from October to December, leave some free days in your plans.
Pattaya, Hua Hin and the Islands Near Bangkok
Pattaya is drier than Bangkok: about 1,106 mm of rain a year, compared with about 1,702 mm in Bangkok. Its wettest month is October (about 224.5 mm), followed by September (about 213.6 mm).
This article gives no monthly figures for Hua Hin, Koh Samet or Koh Chang. For these places, check the 7-day forecast on the TMD website (tmd.go.th) or in TMD's free "Thai Weather" app a few days before you travel.
Official Seasons and the 2026 Forecast
TMD divides the Thai year into three seasons:
| Season | Official dates | What it means for beaches |
|---|---|---|
| Rainy season | Mid-May to mid-October (south-west monsoon) | Andaman coast wettest; Samui fairly dry until September |
| Cool season | Mid-October to mid-February (north-east monsoon) | Andaman coast dry from December; Samui wettest October to December |
| Hot season | Mid-February to mid-May | Andaman coast dry, with February the driest month; Samui in its drier stretch |
In 2026, TMD declared the start of the rainy season on 15 May. Its forecast for the year:
- Total rainfall about 10% below normal.
- The heaviest rain and the highest risk of flash floods in August and September.
- The rain in upper Thailand ending about mid-October, while the Gulf side of the south stays wet until December.
Monthly Rainfall at a Glance
Average rainfall in millimetres (1991–2020). Phuket represents the Andaman coast and Koh Samui represents the Gulf islands.
| Month | Phuket (Andaman) | Koh Samui (Gulf) | Drier coast |
|---|---|---|---|
| January | 49.9 | 126.8 | Andaman |
| February | 24.0 | 64.3 | Both good; Andaman driest |
| March | 80.7 | 115.8 | Andaman |
| April | 135.1 | 82.9 | Gulf |
| May | 236.9 | 131.6 | Gulf |
| June | 249.4 | 133.6 | Gulf |
| July | 240.2 | 117.0 | Gulf |
| August | 308.7 | 102.2 | Gulf |
| September | 350.4 | 117.5 | Gulf |
| October | 336.0 | 294.9 | Both wet |
| November | 178.2 | 444.6 | Andaman |
| December | 82.0 | 263.1 | Andaman |
| Year | 2,271 | 1,994 |
A wet month does not mean rain every day: even in September, Phuket averages about 19 rain days. In the rainy season, plan beach time and boat trips for the morning and keep indoor options for later in the day.
Marine Park Closures
| Place | Closed | Notes for 2026 |
|---|---|---|
| Similan Islands | 16 May to 14 October | Reopens 15 October 2026; open 08:00–16:00 with a daily visitor cap; entry 500 THB per foreign adult, 250 THB per child |
| Maya Bay (Koh Phi Phi Le) | 1 August to 30 September | Reopens 1 October 2026; Phi Phi boat tours run during the closure but cannot enter the bay |
Koh Tachai, in the Similan park, has been closed to visitors since 2016.
Where to Go, Month by Month
November to March: the Andaman Coast
November is a transition month on the Andaman coast: Phuket still averages about 178.2 mm of rain. From December to March the coast is at its driest, and the Similan Islands are open. This is the time for Phuket, Krabi, Phi Phi and Koh Lanta. See our guides on how to get from Bangkok to Phuket, from Bangkok to Krabi, from Bangkok to Koh Phi Phi, from Bangkok to Koh Lanta and from Phuket to Krabi.
Pattaya is fairly dry in these months too: November averages about 56.6 mm of rain and January about 16.3 mm.
April to September: Koh Samui and the Gulf Islands
From April to September, Koh Samui gets much less rain than Phuket. In August, for example, Samui averages about 102.2 mm and Phuket about 308.7 mm. This is the better half of the year for Koh Samui. See our guide on how to get from Bangkok to Koh Samui.
October: Both Coasts Are Wet
In October, Phuket averages about 336 mm of rain, Samui about 295 mm and Pattaya about 224.5 mm. But October 2026 also brings new openings: Maya Bay reopens on 1 October and the Similan Islands on 15 October. The Phuket Vegetarian Festival runs from about 10 to 18 October 2026.
Beach and Sea Safety
- Sunscreen: since August 2021, sunscreens with oxybenzone and other chemicals that harm coral are banned in all of Thailand's marine national parks. The fine can be up to 100,000 THB. Check the label before a Similan or Phi Phi trip.
- Storms: do not shelter under trees in a thunderstorm, and do not walk or drive through floodwater.
- Boats: keep your phone and passport in a dry bag. In the rainy season, pack quick-dry clothes and sandals with a good grip. If the sea is rough, ask your boat operator whether trips are running, or call the Marine Department hotline, 1199.
- Warnings: if a T-Alert message appears on your phone, follow its instructions. T-Alert is Thailand's national warning system, run by the Department of Disaster Prevention and Mitigation (DDPM). Its messages appear on phones in the affected area.
- Heat: drink water often and rest in the shade at midday. For heat stroke (confusion, hot and dry skin), call 1669.
Getting to the Beach by Private Transfer
Smile Taxi Service drives to several beach destinations for a fixed fare. Fares are per vehicle (not per person), one way, with expressway tolls included (THB):
| Route | Sedan | SUV | Van |
|---|---|---|---|
| Suvarnabhumi Airport to Pattaya | 1,200 | 1,500 | 1,800 |
| Suvarnabhumi Airport to Ban Phe Pier (for Koh Samet) | 1,800 | 2,100 | 2,600 |
| Suvarnabhumi Airport to Koh Chang | 3,700 | 4,000 | 4,600 |
| Pattaya to Koh Chang | 3,000 | 3,600 | 4,000 |
| Bangkok to Hua Hin | 2,000 | 2,300 | 2,800 |
| Suvarnabhumi Airport to Hua Hin | 2,000 | 2,200 | 2,800 |
| Phuket Airport to Patong Beach | 1,000 | 1,100 | 1,400 |
| Phuket Airport to Ao Nang Beach (Krabi) | 2,200 | 2,400 | 3,000 |
A sedan takes up to 3 passengers and 2 bags, an SUV up to 5 passengers and 4 bags, and a van up to 7 passengers and 5 bags. For Koh Chang, the car ferry costs extra: 80 THB per person and 120 THB per car.
Airport pickups include 60 minutes of free waiting, counted from the actual landing time. You pay the driver in cash (THB) at the end of the trip. If you can only pay by card, message the team for a PayPal payment link (a 5% fee is added). Cancellation is free up to 24 hours before pickup. After that, a cancellation or change costs 25% (less than 24 h), 35% (less than 12 h) or 50% (less than 2 h) of the price, and a no-show 100%, also when you pay the driver in cash (details). You can see all routes and fares; for a route without a fixed fare, ask for a quote on WhatsApp or LINE. For other ways to travel, see our guides on how to get from Bangkok to Hua Hin and from Pattaya to Koh Chang.
Emergency and Weather Contacts
- Tourist Police: 1155
- Medical emergency: 1669
- Police and general emergency: 191
- Marine Department (boats and piers, 24 hours): 1199
- TMD weather hotline: 1182
- DDPM disaster hotline: 1784
FAQ
When are the Similan Islands open? From 15 October to 15 May. The 2026–27 season opens on 15 October 2026.
Can I visit Maya Bay in August? No. It closes every year from 1 August to 30 September and reopens on 1 October.
What is the best month for Phuket beaches? December to March is the driest time. February is the driest month, with about 24 mm of rain.
Which coast is better in July? The Gulf. In July, Koh Samui averages about 117.0 mm of rain and Phuket about 240.2 mm.
Is Pattaya very rainy in the rainy season? Less than Bangkok. Pattaya gets about 1,106 mm of rain a year, with the most in October (about 224.5 mm).
To plan your beach trip, book your transfer or message us on WhatsApp or LINE.