Weather is probably a major factor when you plan your trip to San Jeronimo, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and May with an average temp of 68°F, while the coldest months are January and February with an average of 63°F. The rainiest months in San Jeronimo are September, June, August, and October, with each month seeing an average of 20 inches of rainfall.