Sounds like you had your mind already made up prior to posting here. Nobody can predict weather - even seemingly weather people on the news for the next day. I thought that the SATs can be arranged to be taken elsewhere than your hometown?

If they can, (where is boeingair - SAT extraordinare person! who could answer that for sure? ), then my recommendation would be to fly to the appropriate city (since you're keen on only flying)e.g., DCA - take the SAT then your other test. Fly out a few days early so that if there is weather you're not delayed; if there isn't weather then you have time to study.