If I want to apply to a school SCEA, will my fall term senior grades be factored into my GPA?
If you apply single-choice early action, your fall term grades will not be factored into your GPA. Early action applications are typically due on November 1st, which is well before your first semester senior year grades have been finalized. In their SCEA admissions decisions, colleges can only consider your grades through the end of junior year.
However, this doesn't mean you should let your grades slip over the course of your senior year. Even if you're accepted based on your credentials at the time of application, colleges will expect to see a continuation of positive academic trends up until the end of high school. In extreme circumstances, failure to maintain your grades can lead a college to revoke its offer of admission.