If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Hai Phong: 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 19°C. The rainiest months in Hai Phong are August, September, July and October, with each month seeing an average of 331 mm of rainfall.