Schools will take into account any extra costs incurred because of study abroad when they create your aid package. So they will probably increase your aid package to compensate for the extra cost of study abroad, but it is unlikely that the entire cost of study abroad will be covered by financial aid.

Schools vary greatly in their procedures paying for study abroad. Some tack it on as an extra fee. Some increase tuition, some will increase room and board because living abroad can be more expensive. These variations in charges will affect financial aid, too. You can ask the financial aid offices of the schools you're applying to how study abroad is dealt with, and they will tell you frankly what the policy is.

I know for certain that some schools do not increase financial aid for study abroad, which can be a surprise for people in their sophomore and junior year. If you're planning on studying abroad, you should definitely make sure that the schools you're applying to will cover at least some of the cost for study abroad with financial aid.

Be very careful about which schools you apply to if you definitely plan on studying abroad. Policies vary greatly, and you don't want to be kept out of the study abroad loop because of financial aid issues.