Do you see yourself eventually living in the south or NY (or a coast)? Not just for college but potentially for your first job. If you want to be a professor (and a lot can change in the upcoming years from undergrad to grad to career), where you go to graduate school matters because traditionally schools don't hire their students - at least not right after they graduate (you can sometimes get a job elsewhere and later return to your program). Now, your decision is about undergrad, but this can impact your graduate school choices.

If you go to GT for undergrad and go to Cornell for grad, you could attempt to come back to GT (or another school), but Cornell wouldn't be immediate. If you go to Cornell for undergrad and GT for grad, you could apply for a job at Cornell but probably not immediately at GT (none of this accounts for the harshness the academic job market, but that's a separate issue). You could go to Cornell or GT for undergrad and neither school for grad (say Cal, UIC, Stanford, MIT etc.), which then would free up both schools.

However, what if you fall in love with your undergrad and stay there for grad school? Then that school's out for the near to even near-far future, as you'll be expected to gain experience elsewhere.

Have you visited both schools? Did one campus speak to you more than the other? Living in New York may also be big change. Have you considered other factors beyond the weather?