Cessna Aircraft Undifferentiated or Other Model
Flight Crew Private; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 13; Flight Crew Total 2522; Flight Crew Type 1833
Human-Machine Interface; Situational Awareness
Conflict NMAC; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Human Factors
While nearing the approach on IFR flight to ZZZ I was cleared for the visual by Center.  Both Center and myself were having communication difficulties generated by radio traffic on frequency.  Center stated their current ATIS was dated and ZZZ Tower was closed. Center gave cancelling instructions but I decided to cancel IFR at that time.  While on approach I accessed ZZZ ATIS but allowed myself to be distracted by several targets on ADSB. I made the mistake of assuming landings were Runway XX; but in fact; one plane was in a left crosswind pattern for [Runway] XYL and one plane was beginning takeoff roll from [Runway] XYL.  I had announced my arrival [on frequency] (Tower).  At the time of seeing the plane in the pattern; I did not realize it was in the pattern and assumed it was departing the airport area.  On short final at approximately 300 feet AGL; I saw the other plane taking off from Runway XYL become airborne. I immediately side-stepped north and then corrected and landed uneventfully on [Runway] XXR.  In retrospect; I should have approached what had become an uncontrolled airport with caution; determined the local traffic and the runways in use before committing to a final on [Runway] XXR.  I should also have monitored the ZZZ Unicom frequency as well.
Cessna pilot reported an NMAC event in the landing pattern.