I have a 2.6 GPA in high school weighted and 2.5 unweighted. I’m sad that I will not get accepted to any UC because of my extremely low GPA. I am a high school senior right now and it is depressing to know that I could have tried in 10th and 11th grade. But as of now I have a 3.7 GPA according to my report card for the 10 week grades. If I just had the motivation and the perseverance to do that in sophomore and junior year, I would not be in this situation. I’m feeling as if I will never get into any UC now. What should I do?
6 of the 9 UC’s offer TAG (Transfer Admission Guarantee) if you meet all the requirements GPA/pre-req and GE courses at your local community college. You can only TAG into one UC but it will be guaranteed so you can still attend a UC if you consider going this route. The other 3 UC’s (UCSD/UCLA/UCB) do not offer TAG but if you perform well at the community college, you can still have a chance for an acceptance also.
http://admission.universityofcalifornia.edu/transfer/guarantee/index.html
If you want to attend a 4 year immediately after HS graduation, there are several Cal States: Channel Islands, Bakersfield, Stanislaus, Dominguez Hills, East Bay that will accept you with your GPA. What are your test scores?
@Gumbymom I plan to attend Pierce College before I transfer to any one of the UCs. TAG is only for one UC and you are guaranteed admission into UCI for example. I plan to major in Mechanical Engineering. As for my scores I took the SAT math 2 and got an 800 and got a 1410 on the SAT.
If you plan to use TAG then your SAT scores will not be considered, so it looks like you have things under control. Best of luck and remember there is more than one way to get you to your goal.
I am not sure this will work. You may want to give it a try: Admission by exam:
http://admission.universityofcalifornia.edu/freshman/requirements/examination/index.html
You would need to take another SAT subject test if you follow this route.
Admission by exam is mainly used to fulfill a-g course requirements and used mainly by home schoolers. This option does not make up for a GPA below the required minimum so it would not be an option for OP. UC TAG by attending a CC is the best route.
To attend a UC, CC with TAG is the best route indeed! You have an incredible chance in that you’re living in California, which offers this kind of second chances to students who were just too immature to achieve at actual potential while in high school but “wake up” as they mature, kick butt in cc, and can graduate from one of the top public university systems in the US. 
If you start at a community college, http://www.assist.org will be your friend in course planning.
For example, here is its listing of Los Angeles Pierce College courses to take for major preparation for mechanical engineering at UCI:
UCI general education is listed here:
You may also complete IGETC in lieu of general education for most majors at most UCs and CSUs.
Note that you must also satisfy base transfer requirements described here:
Have you looked into UC Riverside or Merced? Historically, their admission stats are more forgiving.
@onthewestfence: The UC GPA minimum for an in-state resident is 3.0, so if OP’s UC GPA is below the minimum, it would not be worth applying to any of the UC’s.
@Gumbymom oops 