Transferring to another school at the end of 10th grade is not an easy decision to make. From a college counseling point of view, if you are not challenged enough at the current school and want to transfer, or if there are other inevitable reasons, then usually your motivation will be justified. Other than those reasons, it is recommended to remain at the current school and graduate with good grades. If you still want to transfer, then you might want to consider the following things especially if you plan to apply to selective colleges later.
First, if possible, transfer to a more competitive high school with more rigorous academic programs. Even catholic high schools varies in terms of academic rigor, independent catholic schools (not diocesan schools) tend to have more challenging academic programs and their admission process is more selective. Thus, these schools tend to have higher SAT average scores and to send their graduates to more competitive colleges. Please keep in mind that there are still good diocesan schools too. I am curious which type of school you currently attend at this time. Or you can apply to non sectarian private schools which do not have any association with religious denominations. Many boarding schools are in this category.
Second, you mentioned that you would want to go California. I advise you that the location of the school is at this stage of your high school experience (you are going to be a junior) is not that important. Your focus is to find a right school that helps you to go to a better college if you transfer.
Third, although it is late to make a new application to a good school, there are still chances to get accepted to a better school. This just needs more works to find it. Application process for many good schools is officially over, nevertheless, some of these schools are still looking for good candidates for their schools if students are attractive. Prime Global
