California community colleges have an excellent transfer program for 6 of the 9 UC’s, using TAG (Transfer Admission Guarantee). CSU to UC or UC to UC transfers are definitely possible but the CCC transfer is the best transfer route and given priority.
http://admission.universityofcalifornia.edu/transfer/guarantee/
UC’s accept Junior level transfers (60 semester/90 quarter units) so your HS GPA and test scores are not considered. GPA is the most important factor in transferring from a CCC.
You can use the following link to determine the average GPA required to transfer by major to each campus:
http://www.universityofcalifornia.edu/infocenter/transfers-major