GA pilot reported there needs to be a NOTAM published when the ATC Tower at SQL is closing early. The pilot believes this is a staffing issue and states when the Tower is closed it becomes a safety issue at this busy airport.

Narrative

Planned a flight seeing tour with family today. Checked NOTAMs and conditions 20 hours and then 2 hours pre-flight. Nothing NOTAMed on the Tower being closed. Pre-flighted the aircraft and listened to ATIS at XA:00. ATIS states Tower closure in about 90 minutes without explanation. Spoke with Ground/Tower. Great Controller but clearly working solo on a very busy day.He was clearly overworked. He missed my clearance request which I restated. It was clear he was working alone and handling Clearance/Ground /Tower solo.I've been in and out of SQL for [many] years. This short staffing problem is a consistent problem. I raced back to the field in time to land prior to the Tower closing knowing how this worked out last [time] when the Tower closed early. It was a nightmare; and a real safety issue.I call this out as 1) it should be NOTAMed hours before closing; 2) this seems to happen often at SQL which is a very busy Class Delta airport. I worry that inbound pilots will not know the short staffing problem and resulting Tower closures and there will be accidents. Its clear something needs to be done to improve this contract Tower for the safety of all pilots and passengers.