One complication is it being the first day of class. With some students being commuters, and if it is anything like tropical storm weather (gusty winds and rain), first day attendance could be an issue. Making a trek from one side of campus to the other (like me from ENG to BSN) plus bad weather would be miserable. Also those who miss first day attendance are dropped from the course, but I'm sure they would have accounted for that.
The rain doesn't seem to be that severe or windy, so I didn't see it necessary to cancel all classes, but for the safety of the students and to compensate for commutes, I understand why they closed the campus