People in the UK are using "warm banks" as they struggle to heat their homes amid a cost of living crisis.
More than 3,200 of the warm spaces, run by local authorities and charities, have been established across the country, the Warm Welcome Campaign has said.
Many of them are a third or even half full and offer a variety of services, from hot tea to a place to work.
Daniel Andrews, partnership manager at Wandsworth Libraries, said that since becoming a warm bank, the site had recorded an increase in visitors.
“Our role is to offer a warm, safe space, but also to offer that advice to people who need it,” Mr Andrews told The National.
“Our warm spaces project is about opening up the libraries for extended hours in the new year to help people with the cost of living crisis, to provide them with a safe, warm space to come down to enjoy activities, to engage with other people.”
He said the library would monitor the number of visitors over the coming days.
“The weather's only just started to get really cold,” he said.
“So we'll obviously be monitoring it as we move forward with the temperature dropping, to see whether people are coming down in greater numbers, whether they're extending times within the library, and whether they're asking our staff for more help at this time.”
Save the Children said 194 of 355 councils in England and Wales were directly involved in or supporting groups to open warm spaces this winter.
"Families should not be in a position where they are agonising over whether to put the heating on in sub-zero temperatures," said Becca Lyon, head of child poverty at the charity.
"Parents have told us they will risk going into debt to keep their children warm."
A parent at Wandsworth Library told The National they were visiting with their child to keep warm.
“We are here because outside is very cold and there is no space where you can stay with a little child,” she said.
It comes as forecasters warn temperatures will plummet across the UK at the weekend, with warnings of lows of minus 10°C and up to 10 centimetres of snow in London.
Snow is forecast for Scotland and the south-east of England.
The Met Office said the conditions could lead to travel disruption, especially on Monday morning, and a small chance of some rural communities being cut off, along with a possibility of power cuts and mobile phone coverage being affected.
The UK Health Security Agency issued a level three cold weather alert covering England until Friday, having extended the alert from Monday.
"It is staying cold, with daytime temperatures remaining only a few degrees above freezing in many places over the coming days and overnight temperatures dropping to minus 10°C or lower in isolated spots," said Met Office chief meteorologist Steve Willington.
"Although below average, these temperatures are not that unusual for this time of year.
"There is still a risk we could see some freezing fog in places particularly southern England, especially for Sunday and Monday mornings.
"There is also a small risk of a band of sleet or snow moving into the far south-east on Sunday.
"If this happens it could bring some disruption, especially to rush hour on Monday. A warning has been issued."