Will this NYC apartment be cold this winter?
The radiator is cold and the super swears it's nothing to worry about. Both are telling the truth. Heat season in New York starts October 1, so a cast iron radiator sitting cold at a September or early October showing is doing exactly what it's supposed to, and nothing about the apartment itself can tell you what January will feel like. The building's own complaint record can. Every heat complaint a tenant has ever called in against that address is on file with the city, and read against the building's own size, it answers the question the radiator can't.
A count on its own won't do it. Against a small house, a couple of complaints is a building with a problem. Against a forty-unit rental, it's an ordinary winter. The comparison that answers your question is the building's complaint history set against the number of apartments in it, which is a number you can have before Monday.
What the season actually requires, and who enforces it
New York's heat season runs from October 1 through May 31. During those months, whenever the temperature outside falls below 55 degrees between 6am and 10pm, a landlord has to keep every apartment at least 68 degrees inside. Overnight, from 10pm to 6am, the floor drops to 62 degrees regardless of what it's doing outside. Hot water follows a separate, simpler rule that runs every day of the year, at least 120 degrees, on its own calendar entirely. The obligation itself comes from the city's Housing Maintenance Code, and the Department of Housing Preservation and Development is the agency that enforces it, mainly by taking the call when a tenant reports a violation.
That reporting path is the whole reason the record exists. A tenant who's cold calls 311, HPD logs it against the address, and an inspector follows up if the landlord hasn't already fixed it. Do that enough times at one address and a pattern forms on paper, which is the only place a pattern can form before you've lived through a winter there yourself. That's what you're reading when you check a building before signing: not a promise about this building, but everyone who's already lived there and had reason to call.
How many complaints is normal for a building this size
Every residential building in the city, counting the heat and hot water complaints called in against it across last winter's full season, grouped by how many apartments the building holds, as of August 2026:
| Building size | Buildings | Share with none | Median per 100 units | 90th percentile per 100 units |
|---|---|---|---|---|
| 1-2 units | 595k | 99% | 0 | 0 |
| 3-5 units | 104k | 95% | 0 | 0 |
| 6-19 units | 41k | 77% | 0 | 30 |
| 20-99 units | 22.9k | 43% | 3.0 | 48 |
| 100+ units | 4,625 | 43% | 0.6 | 20 |
Find the size band that matches the building you're standing in. Almost every one- and two-family house had zero heat complaints filed against it all season, so even one or two on a small house is worth noticing, the same way an open violation stands out more on a small building than a large one. A 20-to-99-unit rental sits in a different world entirely: a majority of buildings that size logged at least one complaint, and the busiest tenth logged heat trouble at a rate of roughly one complaint for every two units in the building. That's the band worth reading most carefully, for the same reason it shows up again and again in this library: it's the size where ownership type predicts upkeep least and building management varies the most.
The largest buildings run cleaner than the mid-size ones, the same reversal noise complaints show at the top of the market. A 200-unit building has staff on-site who answer a cold radiator before it becomes a formal complaint. A 30-unit walk-up more often doesn't, and the gap between those two experiences shows up directly in the table.
One more thing the record can tell you: whether a building's complaints look like one loud apartment or a whole building. Among buildings with five or more heat complaints logged last season, about four in five had at least two of those complaints filed on the very same day at some point in the winter, which reads as a shared failure, a dead boiler or a burst riser, rather than one persistent caller. A building whose complaints are spread across separate days all season is closer to the second story. Neither pattern shows up in a raw count. Both show up once you look at the dates.
What to do with it
Pull the address before you sign and read its heat complaint history against the unit count, not on its own. A walk-up with a couple of complaints in a season most buildings its size never logged one is a different building from a large rental sitting mid-pack for its size, and neither number tells you what happens the day you move in, but together they tell you more than a cold radiator in October ever will.
Once you're living there, the record only works if you add to it. Call 311 the first time a room runs cold, note the time and how cold it actually was rather than just "no heat," and put the same complaint to whoever runs the building in writing, separate from the 311 filing, since a landlord who never hears from you directly has nothing on file that they were told. That history becomes the record the next renter reads before signing, the same way this winter's record was written by whoever lived there before you.
Look up any NYC address to see its heat and hot water history next to the building's own unit count, rather than pulling each separately to do the comparison by hand. The city updates 311 daily, so a building's record keeps growing through the season, same as its violation history does the rest of the year.