New York City’s prolonged late-January cold snap did more than freeze the Hudson River and keep residents indoors. It also dealt a blow to the city’s notorious rat population, cutting sighting complaints and, according to rodent experts, likely killing vulnerable animals and suppressing breeding. The freeze arrived on top of an already declining rat-sighting trend driven by aggressive sanitation policy, raising a question the city has never been able to answer with confidence: can weather do what traps and poison alone cannot?
A Below-Freezing Stretch Grips the City
A sustained cold spell settled over New York City beginning January 24, 2026, and held on long enough to visibly alter the urban environment. A satellite image captured on January 28 by NASA’s Earth Observatory showed ice forming across the city’s waterways, a stark visual record of how deep the freeze ran. For more than two weeks, temperatures stayed below freezing, a duration that matters far more to rat survival than a brief overnight dip and that pushed wind chills into ranges where exposed animals could not easily survive without shelter and food.
Complaints of rat sightings dropped during the cold snap, and residents themselves largely stayed indoors. Rodent experts told reporters that the prolonged cold weather could kill some rats and cause others to have fewer babies, potentially leading to a smaller rat population in the spring. That prediction hinges on the length and severity of the freeze, not simply on a few cold nights, because New York City’s dominant wild rat species, Rattus norvegicus, does not hibernate and instead remains active year-round, foraging for food even in harsh conditions and relying on human garbage to sustain dense colonies.
How Freezing Temperatures Kill Rats
The mechanism is straightforward but requires sustained pressure. Prolonged freezing shrinks the available food supply by burying garbage under snow and ice, reduces above-ground rat activity, and suppresses breeding cycles. Sick, malnourished, and juvenile rats are the most vulnerable. Kathleen Corradi, the city’s director of rodent mitigation, and rat ecologist Jason Munshi-South have both described this dynamic on the record: extended cold does not just slow rats down but can kill the weakest animals outright while preventing healthy females from producing new litters. When burrow temperatures drop and food runs short, lactating females may abandon or consume pups, and marginal animals that might have survived a typical winter instead succumb.
Fewer babies born in January and February means fewer rats emerging from burrows in April and May, when warmer weather typically triggers a population surge. That is the core payoff of a brutal winter for a city that treats its rat problem as both a public health threat and a quality-of-life crisis. But the effect is temporary by nature. A single mild spring can erase months of cold-driven attrition if food sources return and breeding resumes at normal rates. The city’s own inspection system reflects this tension: the Department of Health and Mental Hygiene conducts tens of thousands of rat inspections each year, and a failed inspection means inspectors found signs of active rats or conditions that support them, regardless of how harsh the preceding season might have been.
Policy Gains That Preceded the Freeze
The cold snap landed on a city that had already been pushing rat numbers down through deliberate sanitation changes. The Department of Sanitation reported 12 straight months of declining 311 rat sightings, comparing data from December 2023 through November 2024 against the same window one year later. The agency attributed those declines to new trash practices such as containerization pilots, adjusted set-out times, and designated Rat Mitigation Zones, all part of a strategy launched after Mayor Adams appointed Corradi as the city’s first-ever “Rat Czar” in April 2023. Those efforts aim to cut off food and shelter for rats by getting black bags off sidewalks and tightening enforcement on property owners who let burrows flourish…