Planning for the weather is a good way to make your trip to Nakhon Si Thammarat relaxing and enjoyable, especially when you’re splurging. The hottest months are usually May and June with an average temp of 82°F, while the coldest months are January and February with an average of 79°F. The rainiest months in Nakhon Si Thammarat are November, December, October, and January, with each month seeing an average of 13 inches of rainfall.