I am going to be a junior level transfer in the fall and as much as I want to love Berkeley I just don’t feel as sure as others seem to be about going there. I want to have fun and get a good education, and I’m worried Berkeley might be too intense and just not my best fit. The other school I am considering is UCSB. Since I am planning to go to grad school (major is psych), I know employers are going to look more at that school than my undergrad so I would really like to go to Cal for grad school either way. If I declined admission to Cal now and went to UCSB for undergrad instead, would my chances of getting into Cal be much lower than if I went to Cal now? Any experiences with Cal or UCSB for either undergrad or grad school would also be appreciated!
UC is one of the universities which has the “reputation” of having profs [who are the ones who decide who to admit for grad school ] who like to have “fresh blood”, i.e. they want new students to work with within their grad school programs , instead of working with same UG students that they are already familiar with. This can be quite common at some Universities.
That said, what YOU need to do is not even think about where you may or may not get accepted to grad school at this point, and concentrate on doing well in HS.
The Profs at the college you DO get accepted to can give you much more guidance when the time comes, MANY years from now, to think about where to apply for grad school.
Thanks for the reply! I had heard the “fresh blood” sentiment before but I also heard it’s easier to get in for grad school at the school you went to undergrad at so I wasn’t sure which was accurate! I am not in HS though; I have already been accepted to Berkeley and UCSB as a transfer and will start in the fall so grad school is just two years away 
I am having a very hard time deciding between between the two schools and started factoring in grad school chances as something to help me choose where to finish undergrad.
If you are interested in going to grad school, there are hundreds of great U’s that you can apply to. That said,
What you MAY want to do is look at the CV’s of the Psych profs at each U and see where THEY want to grad school. And how many publications they have. I.e. how much they are "known’ or respected in the world of Psychology.
That should and can be a factor to consider when making a decision as to where to go- all else being equal.
LOR’s from your profs will be the single most important factor in getting into grad school, given your GRE scores are high enough and yoiur GPA in your major is above 3.75.
Where THEY went to grad school will give you an “idea” of where they stand " in the world of Psychology. If THEY went to a “top” grad school then a LOR from them will be more likely to open the door for you than a LOR from a prof they dont know.
This is not a blanket truth across universities, across programs or even across professors. Different professors feel differently about this, and different departments are predominated by different opinions. Even within Berkeley, despite the “reputation” they may have, it’s going to be different in physics than it is in English literature, for example.
So the bottom line is no, deciding not to go to Berkeley is not going to affect your graduate school admissions in any way. The professors won’t even necessarily know you applied as a transfer student for undergrad, and they won’t care.