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 Long Hai: The hottest months are usually May and April, with an average temperature of 28°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Long Hai are September, October, July and August, with each month seeing an average of 350 mm of rainfall.