With casement windows, clad exteriors, what do you do to paint the sash when it is cold outside?

Take the sash out and sheet plastic the opening while you do it in a warm room?

Use rigid foam board, cut to size, to block off the opening while you have the sash removed for painting?

Take them out of an entire room, then close the door and let the room get cold, while you take the sash somewhere else for painting?