Weather can make or break a roadtrip, so here's some data about year-round temperatures in Guayaramerin to help you plan yours: The hottest months are usually September and August with an average temp of 81°F, while the coldest months are July and June with an average of 78°F. The rainiest months in Guayaramerin are January, March, February, and December, with each month seeing an average of 14 inches of rainfall.