THAILAND WEATHER

Thailand’s weather changes significantly as you travel from mountain regions to the rice plains and down into palm-lined coastal areas. Most of the country runs on three familiar “seasons”: a cooler, drier stretch which runs roughly November to February, a hot season from March to May, and a rainy season starting in May and ending in October. The exact timing and intensity depends heavily on where you are. Daytime temperatures commonly sit around 28° to 35° Celsius in many lowland areas, with humidity often hovering in the 60% to 90% range. Sunshine can be fierce between showers, so even “cloudy” days can feel bright and very warm.

In the mountainous regions in the north of Thailand around Chiang Mai and Chiang Rai, the air is often at its most comfortable in the cooler months of December and January. During this period, daytime temperatures may be in the mid-20s to low-30s°C, with lower humidity than central parts of Thailand, and with clearer skies that make outdoor exploring much more comfortable. As the hot season arrives in April, the north heats up quickly, and that’s also when smog can become a major issue due to agricultural burning and still air. This smog often peaks in the late dry season around February to April. When the rains begin, clouds build over the mountains in the afternoons, bringing dramatic thunderstorms along with occasional heavy downpours. Landscapes start to become greener by May, especially after the rice fields are planted and start to grow.

The northeast Isan provinces tend to feel hotter in the build-up to the rains and sometimes cooler at night in the dry season. In the hot months, it’s not unusual for daytime highs to push into the mid 30s°Celsius. The first storms can arrive with gusty winds and short, intense bursts of rain. Once the southwest monsoon settles in, humidity climbs and cloud cover becomes more frequent, with rain feeding rice fields and reservoirs. Sunny breaks still pop up, so you might go from blazing sun to a soaking storm and back again within the same afternoon.

Central Thailand which includes Bangkok and the surrounding provinces are known for their heat and humidity all year round, and with less nighttime relief. In the hot season, Bangkok can feel sticky even at 32–36°C, and high humidity makes the “feels like” temperature climb fast. The rainy season brings towering clouds, heavy showers, and the occasional squall. Rain can be spectacularly intense for an hour or so and then vanish. Winds are usually light to moderate inland, but you’ll notice breezier days when monsoon flows strengthen. Cloud cover can swing from hazy bright mornings to stormy late afternoons.

Down in the southern provinces, weather is more coastal and monsoon-driven. The two coastlines have vastly different weather patterns. The Andaman Sea side where you will find Phuket and Krabi often sees its wettest period during the southwest monsoon around May to October. This area has rougher seas, stronger onshore winds, and frequent cloud build-ups. The Gulf of Thailand side of Koh Samui and Koh Phangan can have a comparatively drier mid-year and a wetter stretch later, often around October to December. This weather is influenced by the northeast monsoon, and when the rain arrives, it can be tropical and sudden. Temperatures stay fairly steady year-round, often around 28° to 33°Celsius, but humidity is typically high, and cloud cover can drift in quickly off the water. When the sun does come out it can be very intense.