It may help you to be prepared if you know when you can expect an increase in paranormal activity.

The lunar phases definitely have an effect, during a waxing moon activity will most likely start and/or increase in frequency or intensity. This usually continues through the full moon cycle.   Once the full moon peaks activity should decrease until the next month, when the cycle starts over.

Thunderstorms are another "natural" event that may lend towards increased activity. It is beleived the electrical energy the storm provides can fuel a haunting.

High Adrenalin - meaning any situation which creates excitement or fear.   People who live with chronic stress are prone to have more activity than those that know how to relax.

Other Factors, of course there are dates and times that are important to the spirit itself, such as birthdays, anniversaries, and maybe cycles that they are subject to that we are unaware of.   Unfortunately, we will never know those important dates and as of yet, we do not have a way to understand what we are not aware of, so we are always subject to random events. Or so it seems to us.

Though with a little effort we can "study" the events that do ocurr and from them prepare for the next time.

The link below will take you to a visual lunar calendar.   You can see your expected paranormal activities as the moon goes through it's phases.