Calculate your UC/CSU weighted-capped GPA: http://www.csumentor.edu/planning/high_school/gpa_calculator.asp
Check http://talk.collegeconfidential.com/what-my-chances/1903428-faq-uc-historical-frosh-admit-rates-by-hs-gpa.html for information on past admission rates by GPA (reply #4 for a handy table). But note that if your intended major is an oversubscribed one, admission to the major will be more difficult.