Weather forecasters expect a polar vortex from the Arctic to send temperatures plummeting in the next few weeks.
And pest experts fear a combination of icy conditions and overflowing dustbins could lead to a huge spike in the number of unwanted visitors during the holiday period.
Dee Ward-Thompson, technical manager of the British Pest Control Association, believes the double attraction of food and warmth has the potential to lead to big problems.
She said: “We have had abnormally mild conditions throughout the UK this year and that is likely to have led to an increase in the number of rats.
“Any cold snaps on the way will drive them into buildings in search of shelter and they’ll also go scrounging for food from bins and bird tables.
“So the Christmas and New Year period is likely to provide the perfect opportunity, particularly as it’s party time with fewer bin collections.”
A typical home may have more than a dozen potential entry points for rats, which can transmit a variety of diseases to humans.
They get through gaps as small as 2cm, often using plumbing pipes and unscreened vents or gaps in the eaves and roof edges.
Mrs Ward-Thompson added: “The first evidence of rats in a home is often noises under the floor, in the walls or loft as that’s where most will head to once they’re inside.
“Quite apart from the health risks, they’ll foul water tanks and chew on wood or electrical wires which can cause a lot of damage and poses a fire hazard.
“They’ll also do their best to find sources of food, which means they can soon move to other areas of the house occupied by humans.
“Rats also breed rapidly and will create nests in attics or walls, so it’s vital to act as soon as any evidence is found.”
The BPCA says it’s much easier to prevent an infestation than to get rid of one and says simple precautions can be taken to reduce the risk.
> Inspect properties thoroughly and seal up any external gaps, holes or crevices that could provide rats with a way in.
> Remove potential nesting sites by keeping yards and gardens clean and tidy, cutting back overgrown areas and clearing any piles of wood or debris.
> Ensure doors and windows can be closed properly and that drain inspection covers are well maintained.
> Keep bins well maintained with their lids closed, dispose of rubbish carefully and don’t leave leftover food lying around. Compost heaps should be covered.
> Areas around bird feeders should be kept clean and pet food bowls should not be left out overnight.
It’s important for anyone who does find an infestation to employ recognised professionals.
Mrs Ward-Thompson said: “Rats must be dealt with by a professional pest controller who knows the area in question and their likely habitat, and knows how to treat any particular issue.
“Most people simply want the job done right first time and, by employing a company or individual affiliated with the BPCA, they can be sure they’re using an expert in the field.
“We’ve established strict criteria to ensure the professionalism of our members so controllers carrying our logo will carry out safe, effective and legal treatments.”