The second is it forces you to really know the beach. Noticing the tide and knowing in advance if it's going to be high or low tide reconnects us, if only slightly, to our ancestors who knew when to get up because it was daylight and when to go to bed because it was dark. And also, because Megan the swim instructor's not afraid to get wet (and because we've paid in advance), we go to the beach not only on perfect, sunny, beach days but also on overcast days and on windy days and even on rainy days.
And in a way this gives the beach more depth. If you only go to the beach on ideal beach days then the beach is just a perfect, superficial, place. Always happy. Always smiling. Always aiming to please.
Adverse weather brings out the beach's complexity; it's brooding moments, it's more thoughtful, mature nature. The beach becomes it's own entity and not just something that's there merely for our own private pleasure.
We should shun the fair weather friend and at the very least not limit ourselves to only the fair weather beach day.