  We study the influence of thermal Casimir-Polder forces on the near-surface
trapping of cold polar molecules, with emphasis on LiH and YbF near an Au
surface at room temperature. We show that for a molecule initially prepared in
its electronic and rovibrational ground state, the Casimir-Polder force
oscillates with the molecule-wall separation. The non-resonant force
contribution and the evanescent part of the resonant force contribution almost
exactly cancel at high temperature which results in a saturation of the
(attractive) force in this limit. A dynamical calculation reveals how the
spatial oscillations die out as thermalisation of the molecule with its
environment sets in.
