If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Surat Thani: The hottest months are usually April and March 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 Surat Thani are November, October, May, and September, with each month seeing an average of 11 inches of rainfall.