If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Ca Mau: The hottest months are usually April and March with an average temp of 84°F, while the coldest months are January and December with an average of 80°F. The rainiest months in Ca Mau are October, September, July, and June, with each month seeing an average of 14 inches of rainfall.