It has long been felt that ghosts tread through the world of the living when nights are longer and the temperature is cool. From Halloween to the Winter Solstice, ghost hunters explore the old houses and cemeteries looking for spirits. But, myself, I have found no real difference between winter and summer when it comes to finding ghosts. In fact, there seems to be more activity in summer. This may be due to the fact that summer air is warmer -- heat, like electromagnetic frequencies, is energy. This energy can be used by ghosts much in the same way. From late spring to summer, the air can also be charged with ions as thunderstorms roll in. All of this gives energy ghosts use to move furniture, speak to the living, manifest themselves, and harm all of us.
Don't wait for winter; hunt now.