Weather is probably a major factor when you plan your trip to San Pedro, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and August with an average temp of 81°F, while the coldest months are January and December with an average of 76°F. The rainiest months in San Pedro are June, October, September, and August, with each month seeing an average of 10 inches of rainfall.