We have combined Piezoresponse Force Microscopy and Kelvin Probe Force Microscopy (KPFM) to study screening charge dynamics in written domains on PbZr0.2Ti0.8O3 (PZT) thin film surfaces under a controlled environment and at variable temperature. The screening dynamics decayed exponentially on a timescale of tens of minutes, consistently with what we expected for water-mediated surface diffusion of ionic species. Variable-temperature KPFM measurements showed variations in surface potential due to temporary unbalanced surface screening charges. Low humidity experiments revealed gradual incorporation of positive charges onto the surface, even in a non-reactive environment (N2), as well as deceleration of the screening dynamics upon reversal of the temperature variation. Our work may serve as a guide for future studies on the dynamics and nature of adsorbates on polarized PZT thin films. © 2013 AIP Publishing LLC.