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 Termas de Rio Hondo: The hottest months are usually January and December, with an average temperature of 26°C, while the coldest months are July and June, with an average of 16°C. The rainiest months in Termas de Rio Hondo are January, February, December and March, with each month seeing an average of 251 mm of rainfall.