Planning for the weather is a good way to make your trip to Samut Songkhram relaxing and enjoyable, especially when you’re splurging. The hottest months are usually April and May with an average temp of 85°F, while the coldest months are December and January with an average of 80°F. The rainiest months in Samut Songkhram are September, October, May, and July, with each month seeing an average of 8 inches of rainfall.