There's nothing like an all-inclusive holiday in Nai Muang to revive you, especially when you know what kind of weather to expect. Here's some information to help you decide when to book: The hottest months are usually April and March, with an average temperature of 29°C, while the coldest months are January and December, with an average of 25°C. December and January are the driest months, while September and July are the rainiest months.