Abnormal low and high tides can be caused by the moon, but more frequently they result from sustained high winds. In the Chesapeake Bay it works like this, a heavy, steady blow out of the north pushes water out of the Bay and can drop tides to extreme lows. 

Conversely, winds for a day or two out of the south shoves water north into the Bay creating unusual high tides.

So if you're looking for waterfront property and want a good idea of average highs and lows look for the following. For the high simply look on a piling for the high water stain. For the low look for presence of barnacles. Barnacles need water to live, so the spot at or near where the barnacles grow is reliably the average low.

A less reliable way, but still indicative is to look down the shoreline at the size of the neighbors boats. 

Also important might be to have a real estate agent like Jimmy White who is a boater and knows the waters.

Call me, i love talking about waterfront property