Weather will likely play an important role when you plan your trip to San Jose, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually May and June with an average temp of 81°F, while the coldest months are February and January with an average of 77°F. The rainiest months in San Jose are December, July, January, and October, with each month seeing an average of 15 inches of rainfall.