Weather is probably a major factor when you plan your trip to San Pablo, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and March with an average temp of 66°F, while the coldest months are February and January with an average of 65°F. The rainiest months in San Pablo are October, June, August, and September, with each month seeing an average of 24 inches of rainfall.