How much do colleges look at letter grades compared to overall GPA?

I’m currently a sophomore with a 4.18 weighted gpa (3.67 uw). For the second semester of this school year I’m on track to get straight A’s which would bring up my gpa a good bit considering I’m in every possible honors class I can take. The problem is, this 1st semester of sophomore year I got a C in honors algebra 3-4. I was wondering how hard colleges critique specific letter grades compared to my overall gpa. I’m just afraid that even if I do bring up my gpa quite a bit after junior year, I’m still going to be denied just for having a one C one semester. I’m looking into civil engineering programs at schools like UCLA, UCB, UIUC, and Purdue.

Colleges look at all grades on the transcript. They do not simply look at the overall gpa.

All you can do is your best at this point. For the UC’s, they only use 10-11th grades in their GPA calculation so the C will have an impact but they also look at your Freshman year grades to make sure you passed the a-g course requirements. An upward grade trend will help.
You also happen to be considering the top UC’s, so it will be challenging.
At the end of Junior year calculate out your UC GPA (capped weighted and Fully weighted) to see where you stand.

https://rogerhub.com/gpa-calculator-uc/