This is the ninth consecutive day that fog has appeared in the region, and that would be about as out-of-character for March as those towering Caribbean-like clouds over the region yesterday afternoon.
The peak fog season around here runs from October through February, according to the National Weather Service's long-term records.
Dense fog, defined as a shroud that reduces visibility to a quarter-mile or less, is infrequent in any month.
On average, dense fog shows up only one day in March. However, this month already has had two occurrences, and this morning came pretty close to a third.
"It's a very unusual pattern for this time of year," said Bob Wanton, a meteorologist at the National Weather Service office in Mount Holly.
What is doubly perplexing is that all this fog is occurring even as rainfall is well below normal. So far, only 0.42 inches has been measured at Philadelphia International Airport, pusing 2 inches below normal.
Yet the atmosphere is juiced with moisture. The fog has been rolling in off the Atlantic, said Wanton.
That's due in part to a small low-pressure system off the Delaware coast that has resulted in an onshore flow across the region.
Whatever the causes, the atmosphere is having a hard time believing it's March.