New York City officials are urging residents to prepare for heavy rain and possible flash flooding Sunday morning as a Flood Watch remains in effect through noon and thunderstorms trigger ground stops at JFK, LaGuardia and Newark airports.

The city opened 51 overnight shelters Saturday night for residents who need a safe place to stay, particularly those living in basement apartments and other below-grade dwellings. Service animals and pets are permitted at the sites.

Forecasters say the greatest threat for heavy rain and flash flooding is between 5 a.m. and 10 a.m. Sunday. The National Weather Service expects 1.5 to 3 inches of rain across the city, with the highest amounts possible in eastern Brooklyn and Queens. Localized totals could be higher.

Officials are particularly concerned about flood-prone neighborhoods that have experienced problems in previous storms. Residents living in basement apartments or homes that have flooded before are being urged to move to a safer location if conditions warrant and to closely monitor weather alerts.

NYC Emergency Management activated its Flash Flood Emergency Plan on Thursday, and city agencies have been preparing for potential impacts. Crews have been clearing catch basins and positioning emergency resources ahead of the storm.

"Our crews are clearing catch basins, agencies are preparing and emergency teams will be working through the night while most of the city sleeps," Mayor Zohran Mamdani said. "If you live in a basement apartment, know your exits before you go to bed and be ready to move to a higher floor if conditions worsen. If you're driving Sunday morning, give yourself extra time and never drive through a flooded street. Check on neighbors who may need extra help, and make sure you can receive emergency alerts by texting NOTIFYNYC to 692-692. A few simple steps tonight can help keep you and your neighbors safe tomorrow."

NYC Emergency Management Commissioner Christina Farrell warned that intense rainfall could quickly overwhelm drainage systems.

"Heavy rain can overwhelm streets and drainage systems in minutes, and the most intense rain is expected when many New Yorkers will be asleep," Farrell said. "The strongest storms Sunday morning could drop 2 to 2.5 inches of rain in a single hour. Do not wait until you see water rising to make a plan."

Officials said rainfall rates could reach 1 to 2 inches per hour, with the strongest storms capable of producing up to 2.5 inches per hour. Those rates could lead to ponding on roadways and isolated to scattered flash flooding, particularly in low-lying areas, underpasses, poor-drainage locations and neighborhoods with a history of flooding.

Conditions are expected to improve Sunday afternoon as the storm moves east of the city. Officials continue to advise residents to avoid flooded streets, allow extra travel time, keep devices charged, monitor weather alerts and check on neighbors and family members who may need assistance. Anyone in immediate danger should call 911.

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