Autumn Surf Conditions

Beginning in early September, regular beach goers start to notice a gradual shift in sea conditions. Summer patterns of clear skies, mild ocean breezes, and calm, clear water are interrupted with cloudy skies and gusting wind. Wavelets that once lapped the sand become 3-4’ rollers that challenge surf entry. Crystaline waters turn into a tea-stained medium that, on overcast days, can make a shallow reef dive seem like a blind-folded stumble down a darkened hallway.

These changes are directly attributable to weather conditions shifting toward winter. What were once momentary afternoon showers become days-long blows that can include metric tons of freshwater dropped periodically onto sea and land. Turgid canals dump billions of gallons of filthy runoff into the Intracoastal Waterway, which then disgorges the sludge into the ocean. Prevailing current moves that “fresh” water cloud full of ionized particulates north and south over the reefs.

Compared to saltwater, freshwater from rain and inshore sources has a lighter specific gravity, which causes it to float atop ocean water. At this time of year, the freshwater is cooler than the sea, thus creating an interesting thermal inversion with warm saltwater below and comparatively chilly, murky freshwater above. It might take days or weeks for the two liquids to mix and disburse, during which time one might notice a mirage-like shimmer at the depth where salt and fresh water meet.