Cessna 310/T310C
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 25; Flight Crew Total 1600; Flight Crew Type 600
Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence
Human Factors
Flying to ZZZ; with intended destination ZZZ1. ZZZ1 recently had its IFR approach NOTAMed not available; and a replacement has not been put in with higher minimums or something; so I intended to fly to ZZZ; do an approach into VMC; and cancel and divert to ZZZ1; or cancel before an approach in VMC.Reaching the area; I hit some excellent VMC and cancelled IFR after checking the ceilings/visibility at nearby airports (with ADS-B and XM weather). The airports all showed good VMC with ceilings in the 1;900 to 2;900 foot range and above.I descended to stay below the Class B but nearing the area west of ZZZ the ceilings were lower than reported for any in the area. I slowed; descended to keep in VMC; turned on my radar altimeter; checked terrain warning systems; and proceeded. Eventually I reached 1;000 AGL or so in the 1;200-1;600 feet MSL range and was unable to maintain VMC; which happened gradually due to indistinct bases. Not wanting to descend much below 1;000 AGL (due to many towers in the area and also some areas around there being congested) and with the heavy workload to maintain attitude and altitude I was unable to decide whether to contact a local controller and request an immediate IFR clearance; and/or to proceed or reverse course. The periodic terrain warnings were also annoying and I had no workload-permitting way to silence them since I was hand flying and trying to maintain periods of VMC or at least ground contact.In the end; the ceilings lifted and my unintentional flight into IMC (bottoms of clouds) ended and I made an uneventful landing.Chain of events/Human performance considerations:1. Cancelled IFR believing that reasonably solid VMC prevailed in the area due to all nearby airports reporting at least 1;900 foot ceilings and 9 miles visibility - which was not the case for the entire area. Should probably have kept IFR until Approach had descended me to 2;000-ish which would have put me in clear VMC.2. Unreasonable belief that the weather couldn't 'really be this bad' given all the weather reports (and the ASOS/AWOS); some sort of misguided faith that the weather would be better in just a moment. By the time I realized the true situation my workload had increased to the point where I was unable to look up an appropriate ATC frequency to request immediate IFR clearance. For whatever reason; a 180 turn out of the weather did not occur to me despite the repeated training for VMC into IFR to do just that - I think it was an unreasonable belief in the reported METARs probably.All in all; not remotely my finest judgement or my finest day; despite maintaining positive control of the aircraft at all times (although looking at the track logs does not make it seem that way; since I was constantly varying altitude and occasionally power).Note that the hour estimates above are just estimates; I didn't pull exact numbers from my logbooks.
C310 pilot reported flying VFR into IMC.