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Weather Guide

Surat Thani Weather & Climate Guide 2025

Plan your trip with detailed weather information and seasonal tips for Surat Thani.

Surat Thani is Thailand's largest southern province, renowned as the gateway to world-famous Gulf islands including Koh Samui, Koh Phangan, and Koh Tao. The province combines pristine island beaches, the ancient rainforest of Khao Sok National Park, and the emerald waters of Cheow Lan Lake, making it one of Thailand's most diverse destinations.

Best Time to Visit

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Best Months

December to April

The dry northeast monsoon season brings clear skies, calm seas, and sunny weather across Surat Thani province. January and February are peak beach season with the warmest, clearest water for diving and snorkeling.

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Months to Avoid

October and November

October and November see the heaviest rainfall from the northeast monsoon, with significant flooding risk in Surat Thani City and rough seas making ferry crossings uncomfortable or cancelled.

Climate Overview

Surat Thani province has a tropical monsoon climate with two distinct seasons: the dry season (December to April) and the wet season (May to November). The province receives significant annual rainfall from two monsoon systems — the southwest monsoon brings rain from May to October, while the northeast monsoon delivers heavy rains from October to December. The islands generally experience slightly different weather patterns, with Koh Samui's rainy season peaking in November.

Month-by-Month Guide

What to expect each month of the year.

Jan

27°C/81°F average
Peak dry season — sunny days, calm seas, and excellent visibility for diving and snorkeling. Busy and expensive on the islands.

Feb

28°C/82°F average
Arguably the finest month for beaches — warm, clear, and calm. Whale sharks sometimes spotted at Sail Rock. Peak tourist crowds and prices.

Mar

29°C/84°F average
Still dry and warm. Transitioning to slightly lower crowds as post-peak season begins. Good for all activities.

Apr

30°C/86°F average
Hot and mostly sunny. Songkran (April 13-15) is a highlight. Small chance of afternoon showers towards month end.

May

30°C/86°F average
Transitional month — increasing afternoon thunderstorms but often still sunny mornings. Lower crowds and good value.

Jun

29°C/84°F average
Southwest monsoon brings regular rain, often in afternoon bursts. Mornings still sunny. Great value month for island visits.

Jul

29°C/84°F average
Regular tropical rainstorms but usually with sunny intervals. Khao Sok is especially lush. Good month for diving on Koh Tao.

Aug

29°C/84°F average
Similar to July — regular rain especially on the mainland but islands receive less. Excellent value accommodation rates.

Sep

28°C/82°F average
Heavy rainfall on the mainland. Koh Tao and Koh Phangan can still be decent. Risk of rough seas.

Oct

27°C/81°F average
The wettest month for most of the province. Flooding risk in Surat Thani City. Ferries sometimes cancelled. Not recommended for island hopping.

Nov

27°C/81°F average
Northeast monsoon arrives — Koh Samui's wettest month with heavy daily rains. Koh Tao and Koh Phangan are better but also rainy.

Dec

27°C/81°F average
Early December can still see some rain but conditions improve rapidly. Christmas and New Year see peak prices and crowds. Great holiday atmosphere.
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Seasonal Planning Guide

Complete weather data, packing lists by season, and event calendars.

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Seasonal Breakdown

Detailed information for each season.

🌸 Spring

Mar-May

The transitional period from dry to wet season. March and April are excellent with sunshine and warm seas. May brings increasing humidity and occasional afternoon thunderstorms.

Tips: April is a great month — warm, relatively uncrowded, and good diving visibility. Expect higher prices during Songkran (April 13-15).

☀️ Summer

Jun-Aug

The southwest monsoon brings regular rain, particularly in the afternoons. Mornings are often sunny. The islands receive less rain than the mainland, making them still quite pleasant. Jungle at Khao Sok is lushest during this period.

Tips: June-August is actually quite pleasant for island visits — fewer crowds, lower prices, and alternating sunshine and rain.

🍂 Fall

Sep-Nov

September and October mark the peak wet season. November brings the northeast monsoon's heaviest rains specifically to Koh Samui and the east coast. Khao Sok is very rainy. Rough seas can cancel ferries.

Tips: October-November is the most challenging weather period — travel with flexible plans. November is Koh Samui's wettest month.

❄️ Winter

Dec-Feb

The northeast monsoon delivers dry, sunny conditions to the mainland and west coast islands. December-February is peak season with the best weather for beach holidays and diving. Koh Samui sees occasional short rain showers but mostly sunshine.

Tips: Book accommodation months in advance for December-January. Water visibility for diving reaches annual best levels in January-February.

What to Pack

Seasonal packing recommendations.

Year-Round Essentials

  • Modest clothing (cover shoulders and knees)
  • Comfortable walking shoes
  • Sun protection (hat, sunscreen, sunglasses)
  • Light scarf or shawl (for religious sites)
  • Reusable water bottle
  • Power adapter
  • Basic first aid kit

Hot Weather Additions

  • Lightweight, breathable fabrics
  • Extra sun protection
  • Cooling towel
  • Light colors to reflect heat
  • Sandals with back straps

Cool Weather Additions

  • Warm layers (fleece, sweater)
  • Light jacket or coat
  • Rain gear (umbrella, waterproof jacket)
  • Closed-toe shoes
  • Warm accessories (if winter)

Events & Crowd Levels

Plan around busy periods and special events.

🔴 High Season

December to February (Christmas/New Year peak), plus July-August (European summer)

Higher prices, advance booking essential, crowded attractions.

🟡 Shoulder Season

March-April and May-June — good weather and moderate crowds

Good balance of weather and crowds. Reasonable prices.

🟢 Low Season

September-November — lowest prices but challenging weather

Best deals, fewer tourists. Some services may be limited.

Major Events & Holidays

April 13-15
Songkran (Thai New Year)

National water festival celebrated throughout the province with street water fights and temple merit-making

Full Moon monthly
Full Moon Party

Monthly beach party on Haad Rin, Koh Phangan — dates vary each month based on lunar calendar

October (variable)
Chak Phra Festival

Surat Thani's unique festival with boat processions on the Tapee River — one of Thailand's most distinctive regional festivals

November (variable)
Loy Krathong

Festival of lights with floating lantern releases on rivers and beaches throughout the province

December 31
New Year Countdown

Major celebrations on Chaweng Beach, Koh Samui and throughout the islands

Plan Your Perfect Surat Thani Trip

Get our complete seasonal guide with detailed packing lists, event calendars, and month-by-month planning tips.

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