Koh Samui Weather by Month (Best Time to Visit)

Koh Samui has warm weather all year, but rain patterns are different from much of Thailand. Understanding the island’s seasons helps you plan better beach days, boat trips, and tours. Below is a simple month-by-month breakdown of what to expect.

January – February

One of the best times to visit Koh Samui. Expect plenty of sunshine, calm seas, and low humidity. Great conditions for beaches, snorkeling, and island hopping.

March – April

Hotter months with strong sunshine and minimal rain. April is the hottest month, but still excellent for swimming and boat tours. Songkran (Thai New Year) takes place in mid-April.

May – June

Temperatures stay warm, with occasional short rain showers. Most days are still sunny. Fewer crowds make this a good balance of weather and value.

July – August

Summer months bring warm seas and good visibility for snorkeling. Rain is possible but usually brief. Popular with families during school holidays.

September

A transitional month. You may see more clouds and occasional rain, but conditions are still suitable for travel. Prices start to drop slightly.

October – November

Koh Samui’s main rainy season. Expect heavier rain, rougher seas, and fewer boat trips. November is usually the wettest month. A good time for quieter stays and lower hotel rates.

December

Rainfall drops quickly, and sunshine returns. December marks the start of peak season, especially around Christmas and New Year.

Best time to visit Koh Samui

• Best overall weather: January to April
• Best balance of weather and fewer crowds: May to June
• Quietest months: October to November

Even during the rainy season, Koh Samui rarely sees all-day rain. Most showers are short, with sunshine returning quickly.