Thailand Rainy Season Guide 2026: What to Expect and How to Plan Around It

Thailand's rainy season (called the 'green season' by savvy travellers) is more nuanced than most guides suggest — rain patterns vary significantly by region and typically mean afternoon showers rather than all-day downpours. Understanding the seasons by region: Gulf of Thailand (Koh Samui, Koh Phangan, Koh Tao): rainy season is October–January — the opposite of the Andaman coast; November can see severe storms. Andaman coast (Phuket, Krabi, Koh Phi Phi): rainy season is May–October; June is the wettest month; some small islands close entirely in September–October. Northern Thailand (Chiang Mai, Chiang Rai): rainy season May–October with heavy but predictable afternoon showers; mornings are often clear and beautiful; waterfall season. Bangkok: year-round with a wetter June–October; flooding can affect lower-lying areas in September. What the rainy season is actually like: typically 1–3 hours of heavy rain in the afternoon followed by clear skies and cooler temperatures. The benefits: prices drop 30–50% for accommodation and flights; tourist attractions have a fraction of the crowds; the landscape is extraordinarily green and lush; waterfalls are at full power. Rainy season picks: Chiang Mai for the north — excellent June–September when the mountains are green and misty; Koh Tao for Gulf coast diving (April–October is Koh Tao's good season); Bangkok is year-round with May–October having less smog than the dry season.