If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Guaira: The hottest months are usually January and December with an average temp of 78°F, while the coldest months are July and June with an average of 65°F. The rainiest months in Guaira are October, February, December, and January, with each month seeing an average of 8 inches of rainfall.