How bad is it to have 3 C’s on HS transcript?

I just finished my jr year and I received three C’s this year, before this year I never had one. My gpa is 3.61 and my SAT score is 1290 (1300 super score). My C’s were in physics (sem 2), AP micro, and AP Macro. I do play sports and I am in extracurriculars too. How do my chances stack up for a place like University of Tennessee or IU? Thanks.

Your own guidance counselor can tell you what kinds of grades students have needed to be admitted to those universities in the past.

More importantly, you need to put some thought into the reasons behind the C grades. What were you doing (or not doing) in those classes? What will you do (or not do) in the future to reduce the chance of more C grades?