PA-32 pilot reported receiving a low altitude alert from ATC after encountering icing during cruise. Pilot entered VMC conditions and continued flight.

Narrative

Preflight preparation included a full weather briefing via ForeFlight. No Icing airmets were noted and the local freezing level appeared to be around 7000'. I filed at 5000 feet and after several minutes at this altitude noticed unusual airspeed indications and control feel. Light rime icing began to appear on the windshield and leading edges of the wings. I immediately turned on pitot heat and selected the alternate air source to prevent power loss and regain airspeed indications. I then told ATC I needed lower and they said their minimum was 4000 in the area and cleared me to descend. My altimeter was fluctuating as I descended. Once clear of cloud I thought I was level at 4000; but the altimeter jumped down to around 3400 as the ice melted off the pitot/static blade. ATC issued a low altitude alert at this time as I was below their MVA. I reported clear of ice at 3500 and cancelled IFR so that I could maintain VMC and clear of icing.Significant lessons learned in this case. The indicated OAT never hit freezing; the lowest I saw was 36 degrees. Ice can and will form at this temperature. I learned to take freezing level and icing airmets with a grain of salt. In the future I will add an additional personal comfort factor to these reports and avoid IMC any time the temperature is 40 or below.