Planning for the weather is a good way to make your trip to My Tho relaxing and enjoyable, especially when you’re splurging. The hottest months are usually April and March with an average temp of 83°F, while the coldest months are January and December with an average of 80°F. The rainiest months in My Tho are October, September, July, and August, with each month seeing an average of 11 inches of rainfall.