How bad is a 'C' in high school?

I’ve never got a ‘C’ before, but this year is my junior year and I’m taking some difficult classes.

I’m taking Computer Science 2 AP, Game Design and Programming Honors, English 3 AP, US History AP, Physics AP, Pre-Calculus Pre-AP, and Art 1. I currently have an unweighted GPA of 3.75.

How much will a ‘C’ affect me? What about B’s?

Why are you dooming yourself to a C already? I took challenging classes as a junior, and I would never let the mere thought of a C even cross my mind. Keep your head up, work hard. Remember the C doesn’t come until you slack off.