Seems like there’s an NYC delay program affecting only delta. Here are the details from FAA website with regards to JFK:

ATCSCC ADVZY 033 JFK/ZNY 12/27/2025 CDM GROUND DELAY PROGRAMMESSAGE:
CTL ELEMENT: JFK
ELEMENT TYPE: APT
ADL TIME: 1017Z
DELAY ASSIGNMENT MODE: UDP
ARRIVALS ESTIMATED FOR: 27/1020Z - 27/1559Z
CUMULATIVE PROGRAM PERIOD: 27/1020Z - 27/1559Z
PROGRAM RATE: 5
FLT INCL: CONTIGUOUS US DEP CARRIER DAL ONLY
DEP SCOPE: (2NDTIER) ZAU ZTL ZDC ZNY ZJX ZOB ZBW ZID ZMP
CANADIAN DEP ARPTS INCLUDED: NONE
DELAY ASSIGNMENT TABLE APPLIES TO: ZNY
MAXIMUM DELAY: 259
AVERAGE DELAY: 157
IMPACTING CONDITION: OTHER / OTHER
COMMENTS: DAL MAINLINE AND SUBS ONLY, AIRLINE REQUEST. EFFECTIVE TIME:
271019-271659SIGNATURE:
25/12/27 10:21

Anyone knows what’s going on?

Came to find out exactly this.

Snow stopped a while ago,. Random sampling I see aircraft inbound seem to be either close to on time or up to 1.5 hrs late (sea-> jfk).

It now applies to everyone and not just DL.

My house guests got a cancellation text from DL yesterday afternoon that their JFK-PBI flight for this afternoon was cancelled. Fortunately, we got them on the ISP-VRB Breeze flight, which actually is more convenient on both ends for us and them. Their flight is currently on time as I write this. The house guest said he doesn't like "small airports" because they don't handle the bad weather well when it snows. Uh huh.

My guess would be it's a shortage of ground crews so they don't want arriving planes to clog up the ramp waiting for departing flights to push

It's beautiful when the airport is run by the town (Town of Islip in this case) vs a massive authority like PANYNJ. What was the <24 hour cost on ISP-VRB? Just curious. And what did they pay for DL? I'm assuming they got the DL flight refunded because it was cancelled.

-RM

They bought the top tier economy ticket that included 1 checked bag, extra leg room and refundable. It was about $500 per pax. As it turned out the departure was delayed about 2 hours because ISP only had 3 gates open so arriving flights had to hold on the tarmac to wait for an open gate.

Lots of flights delayed in/out of Boston. They told me that the biggest issue now is getting crews where they need them to be due to the rolling delays.

We got very, very lucky. Six of us supposed to be flying post-cruise FLL to Boston. Happened to wake up when the cancellation notice hit at 1:30am. Immediately got in touch with Delta via text on app, which is always a dicey proposition. I pointed the rep to six remaining seats on PBI-BOS, which was five hours delayed, giving us plenty of time to get to the airport, and we can wait in the lounge. Definitely could have been worse.

Yeah BOS is a mess entirely due to Delta crew management issues. Airport itself had little to no wx delays, just some simple deicing yesterday am... and DL is still showing cancellations running through today.

JetBlue has more flights cancelled and more flights delayed at BOS than DL today.

MSP had a lot (about 6 inches with high winds continuing) of snow yesterday, with over 200 cancellations reported at the airport (all carriers).

When a hub has problems, it tends to affect the entire system.