Due to the fact that fewer vets are carrying out non-essential neutering procedures during the pandemic, charities are worried about the number of female cats becoming pregnant, and the added number of kittens who may need a home as a result.
They're warning owners of un-neutered cats (both male and female) to try and keep them indoors throughout lockdown, in order to prevent a seasonal boom in kitten numbers.
Since the beginning of lockdown, the RSPCA has taken more than 600 cats into its care - which is more than any other pet - and there are concerns that the situation is only going to escalate.
Dr Samantha Gaines, head of the RSPCA's companion animal department, said: "The kitten season this year will continue despite Covid-19 and so the charity is bracing itself for even more cats."
Meanwhile, Cats Protection voiced similar concerns.
In a survey of 1,000 cat owners, the charity found that 86 per cent did not know that a female cat could have up to 18 kittens a year.
Plus, 77 per cent were unaware a female cat can become pregnant as early as four months of age.
Sarah Reid, the charity's acting head of neutering, said: "Our fear is that many kittens born this summer will be left on the streets.
"This is because Cats Protection is full up with cats and, owing to Covid-19, is unable to admit many more except in emergency cases."
One man from Harrow experienced just this issue, as he ended up with 17 cats during lockdown after his un-neutered female cat fell pregnant.
And things got so out of control that he ended up with multiple litters being born at the same time.
Plus, the RSPCA rescued a total of 22 cats from one single household in Weston-super-Mare last week.
In the group, there was 14 different kittens from three different litters, and several of the adult cats were pregnant, too.
The charity has had 6,630 incidents reported to them involving cats since March 23, at the start of lockdown.
Although the volume of calls being received during lockdown is lower than it was during the same time last year, the charity is now only responding to emergencies, and they fear it could actually be much higher.
As well as keeping female cats inside, Cats Protection is also advising pet owners to keep their male and female cats apart if they are un-neutered.
If your cat isn't neutered, take note - this is so important!