You are over thinking this way too much.
The best case scenario is that the cumulative weighted GPA is required to be at least a 3.0
The worst case scenario is that the SEMESTER weighted GPA is required to be at least a 3.0.
If you can make sure that you meet the worst case scenario, then you will automatically meet the best case scenario.
Simple words: Just get a weighted 3.0 THIS semester and don't worry about last semester. If you can pull off a 3.0 weighted this semester, you're good to go. I'm sure that wouldn't be hard considering it's a WEIGHTED GPA and the fact that you got into UCSD means you're more than capable of pulling off a good GPA.