If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in An Thoi: The hottest months are usually May and April with an average temp of 83°F, while the coldest months are January and December with an average of 81°F. The rainiest months in An Thoi are September, July, October, and August, with each month seeing an average of 13 inches of rainfall.