I don't remember the exact numbers, but every semester I had somewhere between 3.5 - 4.0+. You may already know this, but normally the max GPA is 4.0. However, AP courses contribute more than a normal course does so it's possible to achieve above a 4.0 GPA. Junior and senior year I was taking 3-4 AP courses so my GPAs were quite high especially during those semesters.
My SAT score was decent. Wasn't terrible, but wasn't anything special. I took it twice and unfortunately got a slightly lower score the second time around.
They also look at if you do any extracurricular activities like clubs, sports, community service, etc.
I have seen a fair amount of people get accepted into UC's or CSU's with decent to low GPA's, but in most cases they also were pretty outstanding when it came to those extracurricular activities and/or what they wrote about their personal life when applying for the universities.
It was kinda disheartening when all the people around me were telling me they were getting accepted into UC This and CSU That, meanwhile all I was getting were sorry letters from them. I'd be lying if I said I wasn't a bit jealous. It made me feel like I was pretty dumb actually. I eventually got denied from almost all the schools I applied for and was waiting on 1 more. Phew, luckily I got into that one though.
TLDR: Universities are competitive unless you're a complete all-star. And also quite expensive.
I know I made it seem pretty dreadful but I don't mean to discourage you. Also normally you need to pay to apply to universities but depending on your family's income you can get waivers, meaning you can basically just apply to these universities for free. Might as well give some of them a shot, you never know. They do give you chances to talk about your personal life so that might help you out. Universities also tend to promote diversity on their campus so you may have some talents that many others may not have which can help.