Planning for the weather is an important factor for making your trip to Termas de Rio Hondo a success, especially when you’re splurging. The hottest months are usually January and December with an average temp of 79°F, while the coldest months are July and June with an average of 60°F. The rainiest months in Termas de Rio Hondo are January, February, December, and March, with each month seeing an average of 10 inches of rainfall.