The rainy season in much of Thailand runs from May to October, with September and October being the height of the monsoon season. The rainy season in Koh Samui and the south east of the Thai peninsula runs from November to March. Heavy storms during the monsoon can cause disruption and damage including flooding and landslides.
The Mekong River Commission posts official updates on the Mekong River on its website.
Lakes, caves and waterfalls are particularly prone to dangerous flash flooding during the rainy season.