If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Samut Prakan: The hottest months are usually April and May with an average temp of 86°F, while the coldest months are December and January with an average of 82°F. The rainiest months in Samut Prakan are September, October, July, and August, with each month seeing an average of 7 inches of rainfall.