A sampling of colleges of various types:
Stanford University (wealthy private university with hospital and medical school on campus):
https://vaden.stanford.edu/about/hours
https://vaden.stanford.edu/get-help-now/after-hours-services-when-vaden-closed
Santa Clara University (less wealthy private university):
https://www.scu.edu/cowell/
San Jose State University (public university):
http://www.sjsu.edu/studenthealth/
Mission College (public community college):
http://missioncollege.edu/student_services/health-services/index.html
It appears that the expectation for most students at most colleges is that they be able to seek medical care in the community if the campus student health center is closed or if it does not offer the needed services for the situation.