Rain developed across the area ahead of an approaching warm front, consolidating into a slow-moving band of heavy rain west of New York City by late morning. Precipitable water values increased from 1.84 on the morning sounding from Upton, NY to 2.13 by evening. Both of these values are above the 90th percentile based on a sounding climatology, with the 2.13 precipitable water value on the evening of the 25th a record for the date. Rainfall amounts generally ranged from 1-4 inches across New York City and Westchester County, and 2-5 inches across portions of northern Suffolk County. The ASOS at Central Park recorded 2.08 inches of rain while the ASOS at the White Plains Airport recorded 4.43 inches of rain during the event. Farther east, 4.27 inches of rain was reported by a CoCoRaHS observer in Port Jefferson Station, while a member of the public reported 4.53 inches of rain in Setauket.

Flash Flood in WESTCHESTER, NEW YORK
From 25-SEP-18 13:12:00 to 25-SEP-18 14:55:00 (EST-5)
Location: HASTINGS ON HUDSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Bronx River Parkway was closed due to flooding in White Plains between Greenacres Avenue and Tarrytown Road.

Flash Flood in QUEENS, NEW YORK
From 25-SEP-18 15:15:00 to 25-SEP-18 15:45:00 (EST-5)
Location: FLUSHING ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

All southbound lanes on Bell Boulevard closed at 208th Place in Bayside with two feet of standing water. The police were on the scene.

Flash Flood in SUFFOLK, NEW YORK
From 25-SEP-18 19:20:00 to 25-SEP-18 20:00:00 (EST-5)
Location: STONY BROOK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The south entrance to Stony Brook University Hospital in Stony Brook was flooded and impassable.

Flash Flood in SUFFOLK, NEW YORK
From 25-SEP-18 20:00:00 to 25-SEP-18 20:00:00 (EST-5)
Location: PORT JEFFERSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Route 25A was closed due to flooding in Port Jefferson between Sheep Pasture Road and Route 112/Patchogue Road.

Flash Flood in BRONX, NEW YORK
From 25-SEP-18 14:00:00 to 26-SEP-18 04:15:00 (EST-5)
Location: FORDHAM
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Bronx River at the New York Botanical Garden exceeded its flood stage of 3.0 feet at 2:00pm EDT. The river then proceeded to rise above its moderate flood stage of 3.5 feet at 3:15pm EDT and above its major flood stage of 4.0 feet at 5:45pm, cresting at a height of 4.16 feet at 8:30pm EDT. The river fell back below flood stage at 4:15am EDT on September 26th.

Flash Flood in BRONX, NEW YORK
From 25-SEP-18 12:22:00 to 25-SEP-18 14:55:00 (EST-5)
Location: WILLIAMS BRIDGE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The Moshulu Parkway was flooded at the I-87 interchange in the Bronx.

Flash Flood in SUFFOLK, NEW YORK
From 25-SEP-18 19:30:00 to 25-SEP-18 20:00:00 (EST-5)
Location: BELLE TERRE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Widespread flash flooding was reported across the village of Port Jefferson, with some of the most significant flooding occurring on Main Street near Maple Place. Water was 3-4 feed deep in several locations with multiple cars stuck in flood waters. The flooding resulted in people being rescued from both the Old Fields Restaurant on Wynn Lane and Theatre Three on Main Street, as well as damage to a combined retail/residential building located at 464 Main Street.