Weather will likely play an important role when you plan your trip to San Fernando, 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 74°F, while the coldest months are January and December with an average of 71°F. The rainiest months in San Fernando are May, September, October, and June, with each month seeing an average of 13 inches of rainfall.