Why Warmer Weather Is Increasing Rat Activity (And What Pest Controllers Should Do About It)

This week, the UK is experiencing an unexpected heatwave, with temperatures significantly higher than usual for this time of year.

While many people are welcoming the sunshine, this sudden surge in warmth is having an unwelcome side effect: a sharp increase in rat activity, particularly within drainage systems.

For pest controllers, understanding how and why this is happening — and acting fast — is critical for protecting homes, businesses, and public spaces from infestation.

Why Rats Become More Active During Heatwaves

Rats are remarkably sensitive to environmental changes. The recent rise in temperatures is creating the perfect storm for a spike in rodent activity:

• Breeding Booms in Warm Weather

Rats reproduce year-round, but warmer temperatures accelerate their breeding cycles dramatically.

In ideal conditions like we’re seeing now, rat populations can double or even triple in a very short time. A single pair of rats, if left unchecked, can produce over 1,000 descendants in just one year.

• Increased Food Availability Outdoors

Warm weather means more outdoor activities — barbecues, garden parties, gatherings — and with them, a surge in food waste.

Overflowing bins, leftover scraps, and litter all provide easy, high-calorie meals for rats, encouraging them to stay close to residential and commercial areas.

Drains: The Hidden Superhighways for Summer Rats

When it comes to rat infestations, most people’s minds jump to visible entry points — gaps under doors, cracks in walls, or holes around pipes. However, one of the biggest vulnerabilities is hidden underground: the drainage system.

During warmer weather, drains become even more attractive and accessible for rats, making them a key contributor to summer infestations.

Here’s why drains are considered the "superhighways" for rats — especially right now:

• A Protected Underground Network

Drains offer rats safe, concealed routes to move between different areas without ever being seen. Unlike above ground, where predators and humans pose risks, underground movement is protected — allowing rats to travel large distances unnoticed.

This ability to operate covertly makes infestations much harder to detect until serious damage has already been done.

• Direct Access to Buildings

Damaged drains, open gulleys, cracked pipes, and poorly fitted outlets act as entry points directly into properties. From the drain system, rats can quickly access:

• Kitchens

• Basements and cellars

• Floor voids

• Wall cavities

Once inside, they establish nests, contaminate food stores, and cause significant structural damage — often without immediate signs on the surface.

• Dry, Comfortable Conditions in Hot Weather

Typically, winter flooding makes it harder for rats to use drainage systems extensively. However, in hot, dry weather like we’re seeing now, drains become drier, warmer, and more scalable. This shift provides ideal nesting and travel conditions.

Why Acting on Drain Issues is Crucial for Summer Pest Control

If pest controllers focus only on surface-level prevention — sealing up visible holes or setting traps — they risk missing the real source of infestations. The underground route is how many rats are gaining entry in the first place.

By identifying vulnerabilities and installing RatGates to block rodent access at key drainage points, pest controllers can cut off rats at their primary entry routes, offering long-term protection for residential and commercial clients alike.