If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Thong Chai: The hottest months are usually April and May, with an average temperature of 28°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Thong Chai are September, October, July and May, with each month seeing an average of 252 mm of rainfall.