If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Thanh Hoa: The hottest months are usually June and July, with an average temperature of 29°C, while the coldest months are January and December, with an average of 20°C. The rainiest months in Thanh Hoa are August, September, July and October, with each month seeing an average of 309 mm of rainfall.