Skyhawk 172/Cutlass 172
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 37; Flight Crew Total 315; Flight Crew Type 275
Time Pressure; Workload; Distraction
Airspace Violation All Types; Deviation / Discrepancy - Procedural FAR
Flight Crew Returned To Departure Airport
Weather
I successfully convinced myself that at night; if there's any weather at all; I should be in on an instrument flight plan. I arrived at SQL having picked up an IFR clearance en route because the weather was reported as marginal; but on arrival into the Bay Area; things were almost totally clear south of OAK. I waited for a passenger for about 30-45 minutes before departing back to the east. I chose not to pick up an IFR clearance for the return flight because it had been clear on the way in and the weather reports weren't any different. We departed VFR and began a slow climb underneath the SFO Bravo shelves to get out past Sunol Grade when we began to contact the bases around 1;800-2;000 feet. I descended back to 1;500 feet and worked south towards RHV for a little while thinking I had just picked a bad spot. At some point near VPNUM it felt as if the clouds were descending and the terrain was rising; and having read a lot of reports of other people making this mistake; I made an immediate 180 and decided to return to Palo Alto to land and pick up an IFR clearance. I was listening to but not talking to Norcal; who had been really busy on my approach; and believe but have not confirmed they cannot issue new clearances that low over the bay due to MVAs? Also decided it was safer to be on the ground copying a clearance rather than trying to navigate at night with lowering layers; complex airspace; and low altitude. On the return to PAO I started off direct before almost blundering into NUQ's airspace although I believe I avoided it by maybe half a mile. In the end; landed safely at PAO; called Norcal for a clearance from the ground; and continued on our flight IFR and much more comfortably.Lessons worth learning: Marginal VFR at night is 100% IFR worthy; even if you have to deal with more complicated clearance delivery; NUQ's airspace where it intersects with PAO's continues to confuse me.
Cessna pilot reported flying in marginal VFR weather at night; and returning to departure airport to pick up IFR clearance.