Most experts recommend scheduling pressure washing in spring or fall. Temperature extremes make pressure washing more difficult. For example, too much heat will evaporate the water before it cleans the surface, while frigid temperatures might freeze the water during the cleaning process.   A spring power wash eradicates the dirt and grime that has accumulated over the winter. Power washing in the fall takes care of leaves and other debris before winter so that it doesn’t create a conducive environment for mold growth or settle in.