Climate change and rodents: why winter no longer keeps pests out

Quick overview

• Warmer winters give rodents more time outdoors to forage and breed.
• A 2025 study linked rising rat populations in 11 of 16 cities to warming temperatures.
• Rodent pressure is shifting from a cold-weather issue to a year-round one.
• Drought can push rats and mice indoors in search of water.
• Monitoring and exclusion matter more now than they did under the old seasonal pattern.

Most facility teams have treated rodents as a fall and winter problem for years. Cold weather pushed rats and mice indoors looking for warmth, so pest programs ramped up before the first frost and eased off by spring. That pattern is changing. The link between climate change and rodents has become clear enough that it is reshaping how commercial facilities need to plan, not just when they schedule service, but how consistently they monitor for activity.

Here is what the research shows, and what it means for your building.

How warmer temperatures drive rodent population growth

Rodents are cold-sensitive. When temperatures drop, rats and mice spend less time above ground, which naturally slows their breeding and limits how far they travel to find food. Warmer winters remove that natural check.

A 2025 study published in Science Advances analyzed data from 16 cities and found that 11 had significant increases in rat numbers, including Washington, D.C., New York City, and Amsterdam. The researchers found that the extent to which a city had warmed over time was the strongest single factor behind rising rat populations, more influential than population density or urbanization. Even a week or two of extra warmth can let rats forage longer and fit in another breeding cycle.

What this means for rodent population growth

More time foraging generally means more litters per year, and more litters mean larger populations pressing against buildings, loading docks, and storage areas. For facilities already managing rodent entry points, that added pressure compounds over time rather than resetting each winter.

The shift away from a predictable pest season  

Pest activity used to cluster around the coldest months. As winters trend milder in many regions, that pattern is breaking down. Warmer fall and winter temperatures can reduce the natural die-off that once thinned rodent populations before spring, leaving more animals alive to breed as the weather turns.

The result is less predictable timing. Instead of a short, intense winter push, some regions now see steady or rising rodent activity stretching across spring and summer as well, right when reproduction peaks. A pest program built around a once-a-year winter inspection is likely to miss activity that now spreads across most of the calendar.

Drought adds another factor 

Temperature is not the only driver. Periods of drought reduce the water and food rodents can find outdoors, pushing them toward buildings, irrigation systems, and landscaped areas where resources are more reliable. For facilities near open land or with exposed utility lines, that raises the odds of an indoor problem independent of the season.

Why this matters more for certain industries 

A longer, less predictable rodent season raises the stakes for sectors where the margin for error is already thin:

• Food and beverage facilities, where contamination carries direct compliance and reputational risk.
• Healthcare facilities, where hygiene standards leave little room for pest activity.
• Warehousing and logistics, where large footprints and frequent deliveries create constant opportunities for rodents to enter.

None of this means rodent activity is impossible to manage. It means the fundamentals - exclusion, sanitation, and regular monitoring, need to run on a longer calendar than they used to.

Building a year-round rodent prevention plan 

The core defenses against rodents have not changed. What has changed is how long those defenses need to stay active. Sealing entry points, tightening waste storage, and checking vulnerable areas now need to happen across the full year rather than concentrated before the first cold snap.

An integrated pest management approach fits this shift well, since it prioritizes prevention and addresses the conditions that let rodents establish themselves, rather than reacting only after activity appears. Pairing that prevention work with ongoing rodent control and ongoing monitoring gives facility teams an earlier signal when activity starts climbing, regardless of what month it is.

Staying ahead as the climate shifts 

Climate change and rodents are now part of the same planning conversation for facility managers. Warmer winters, longer breeding windows, and drought-driven movement all point toward steadier, less seasonal pressure than facilities have historically planned for. The teams that adapt are the ones that trade a winter-only mindset for consistent, year-round attention backed by real monitoring data.

Rodent pressure no longer waits for winter, so your pest program shouldn’t either. PestConnect tracks activity around the clock and flags changes as they happen, helping your team respond earlier and maintain consistent protection across every season. Get in touch with our commercial pest control team for a free inspection to help assess your facility's current risk and build a plan suited to year-round conditions.