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 Lago Sul: The hottest months are usually September and October, with an average temperature of 23°C, while the coldest months are July and June, with an average of 21°C. The rainiest months in Lago Sul are December, November, January and March, with each month seeing an average of 267 mm of rainfall.