While my counselor has assured me in the past that this rarely happens, I hear stories on the internet that the University of Washington takes back acceptances if they see you’re slacking.
This semester has been pretty rough on me and I went from A’s and a few B’s here and there to…not as good grades. I’m estimating:
IB English: C+/B-
Theory of Knowledge: B
IB Math Studies: D+
Yearbook: A
IB Physics: B-
IB History: B-
Can anyone honestly tell me if they think UW is gonna take back my acceptance? I’m stressed out of my mind.
I forgot to add a C in IB Spanish 
C’s are not a problem. The usual rule is no D or F grades. You need tosit down with your counselor. I know you have mono, so your counselor should be intervening with your chose university on your behalf and make sure they are aware of that. Between all of you, I am sure soemthing can be done to work the situation out. You need to meet with your counselor right away.
Agree with @Lindagaf I don’t know the exact policy at UW but it does happen that students get rescinded, put on academic probation etc. Every year our HS sends a package of these type of letters to graduating seniors that people in the HS had received in past years (names blocked out of course). The general rule on CC is to avoid D’s, F’s, and felonies. On another thread you said you had mono so you should ask your guidance counselor to write an explanation of your illness and send it along with your final transcript.
Addendum: You should also ask your guidance counselor what grades get sent on the final transcript. The grades you posted above are semester grades. If your year-end grades will be all C or better and if your HS only sends the year-end grades to colleges then you would probably be OK. Still, it wouldn’t hurt for your GC to explain your illness in a note attached to the final transcript. I don’t think any college would want to penalize you for having mono.