LI September rain record: 8.75 inches fell in Islip with half from recent nor'easter

The lingering nor’easter that swept across Long Island last weekend helped set a record for the month of September: 8.76 inches of rain fell on Islip, according to Joe Pollina, a meteorologist at the National Weather Service in Upton.

The nor'easter contributed more than half the total rainfall, said Geoff Bansen, a NewsdayTV meteorologist, along with blustery winds and battering waves.

The previous record, just shy of 7.5 inches, was set in 1966, Pollina said.

The record-breaking rain arrived in the midst of an apparently supersized El Niño climate pattern that has been developing this fall. Typically El Niño years are marked by suppressed hurricane systems in the Atlantic — and that’s been true so far this year.

But nor’easters are generated by a different combination of atmospheric factors, Pollina said, such as the shifting of the polar jet stream toward the south, so their frequency and ferocity are not necessarily governed by El Niño.

Pollina said it’s impossible to say if this could be a heavy year for nor’easters because those storm systems can be forecast just a couple of weeks in advance.