Every autumn the same pattern repeats in homes across the country: scratching in the walls, gnaw marks in the pantry and droppings behind the fridge. As the temperature drops, rats move indoors – and autumn is by far the most common time for rat infestations. The good news is that you can stop them, if you act before they settle in.
Quick answer: Rats move indoors in autumn when the temperature drops and they look for warmth, food and shelter for the winter. They get in through gaps as small as 2 cm at the foundation, vents and pipe penetrations. Seal the entry points before September and remove food sources outdoors, and you'll stop them before they settle in.
Why do rats come indoors specifically in autumn?
Rats come indoors in autumn because they are looking for three things that become harder to find outside once the cold sets in: warmth, food and shelter. In summer rats do fine outdoors, but when nights turn cold and the harvest is in, both food and warm hiding places dwindle. Your heated house then becomes the most attractive place in the area.
Unlike many other pests, rats do not hibernate. They are active all winter and need a safe, warm place to overwinter – ideally close to a steady food source. A house with heat leaks, accessible entry points and food within reach meets all three needs at once.
When is the risk highest?
The risk is highest from late August to November, with a clear peak in October. During these months rodents actively look for winter quarters just as nature's larder empties. Activity rises noticeably as soon as night-time temperatures drop below ten degrees.
That means the best time to prevent them is late summer – in August, before the rats start moving in. If you wait until you hear the first sounds in the wall, the infestation has often already begun.
The most common ways into the house
Rats get in through surprisingly small openings – a brown rat squeezes through a gap of just 2 centimetres. The most common entry points in autumn are:
- Cracks and gaps in the foundation and base wall near ground level
- Loose pipe penetrations for water, drains and electricity
- Vents and air intakes without mesh, and broken ventilation grilles
- Gaps at the eaves, bargeboards and chimney – rats are good climbers
- Gaps around doors and basement windows that don't seal tightly
Trees and bushes growing up the façade act as ladders to the roof, and woodpiles against the wall provide both shelter and a way in. If you want to understand the whole picture around rodents in the home, read our guide to rats in the house.
How to prevent rats in autumn – step by step
The most effective protection is to make the house inaccessible and the plot unappealing before the rats move in. Do this:
- 1. Seal the entry points. Walk around the house in August and seal gaps at the foundation, pipes and vents with steel wool and metal mesh – rats gnaw through foam and wood, but not metal.
- 2. Remove food sources outdoors. Pick up fallen fruit, bring in bird feeders and store rubbish and animal feed in tightly sealed containers.
- 3. Clear along the house wall. Cut back bushes by the façade, move the woodpile at least half a metre from the wall and keep the area under decking clean.
- 4. Check regularly. Inspect the foundation, basement and attic through the autumn so you spot early signs right away.
- 5. Add preventive protection. An electronic rat repeller uses ultrasound and bioacoustic signals to make the environment unwelcoming to rats, without poison or chemicals. It suits a poison-free, preventive role in spaces like storage rooms, garages and crawl spaces – not as an emergency fix for a large, established infestation.
Natural scents can reinforce the effect in exposed spots. Here you'll find scents that keep rats away.
Signs the rats are already inside
If prevention comes too late, rats give themselves away through clear traces: scratching in walls and ceilings at night, dark droppings of 1–2 cm along walls, gnaw marks on wood and cables and a sharp smell of urine. The sooner you spot them, the easier it is to break the infestation. Go through all the signs of rats so you don't confuse them with mice or other animals.
What to do now
Is it still late summer or early autumn? Take the chance to seal the entry points and clear the plot now – prevention is cheaper and easier than control. If you already hear sounds in the walls, act quickly with sealing and traps along the rats' runways. With the right measures at the right time, you keep the house rat-free all winter.
Frequently asked questions
Can rats come in through the drains?
Yes. The brown rat is a strong swimmer and can, in rare cases, come up through the drains and toilet, especially in older properties. A drain rat blocker (non-return valve) reduces the risk.
How cold does it have to get before rats move indoors?
There is no exact threshold, but rats start actively seeking shelter indoors when nights turn cold and outdoor food dwindles – often as early as September, when night-time temperatures drop below 10 degrees.
Which month has the highest risk of rats?
The risk is highest from late August to November, peaking in October. That's when rodents seek winter quarters just as the harvest ends and outdoor food runs out.
