Age UK says it has heard reports of people being so worried about putting their heating on that they are living in cold houses in Shropshire.
At the same time, Shropshire Council is also set to engage its Severe Weather Emergency Protocol on Tuesday and invite rough sleepers off the streets of Shrewsbury into a shelter.
Our picture shows autumn hanging on at The Quarry in Shrewsbury but that is set to change to much colder conditions, with frosts on the cards with temperatures even during the day struggling to rise above freezing.
"Please do not switch the heating off," said Heather Osborne, chief executive of Age UK Shropshire Telford & Wrekin. "Have at least one room where you keep the heating on. Turn down but not off as it will be more expensive."
The Age UK call comes as the Met Office has issued a severe cold weather alert for England, warning that plummeting temperatures later this week could increase health risks to vulnerable people and disrupt deliveries.
The level three, or amber, cold weather alert was issued on Monday morning and warns of severe conditions in England between 6pm on Wednesday and 9am next Monday, December 12.
Ms Osborne added: "People are worried about the costs but it is more important to think of your health. It can be very detrimental to health to be in a cold home. We have staff who are meeting people who have not put their heating on."
She said that extra help is available to people, and Age UK can help to maximise people's benefits and other financial assistance. Marches Energy Agency can also help provide advice to people at this dreaded time of the year.
"It is a false economy to think that it will be cheaper to switch the heating off because we are told that it is more expensive to heat up a room from cold than to keep the heating on at a low level," she added.
"If people are really worried they can call us for help on 01743 223123 and we can help them to maximise their income and to make sure they get all the help they need."
Councils are also running warm spaces in many public buildings in the county, with information accessible online.
Ms Osborne said Age UK could help people who wish to know more to find out where their local warm spaces are.
A night shelter will be opening for rough sleepers in Shrewsbury as Shropshire Council says it is likely that a Severe Weather Emergency Protocol (SWEP) will be activated on Tuesday evening right through to the morning of Friday, December 16 as forecasts are stating temperatures of 0 degrees Celsius and below.
A spokesman for Shropshire Council said: "We will be making the decision on whether we will activate SWEP day to day and will be emailing our partner agencies each morning so that they can spread the word to our rough sleeping cohort in Shropshire.
The night shelter will open its doors at 10pm and will close at 8am the following morning on each day that SWEP is activated.
"We will be asking those who are rough sleeping to arrive between 10pm and 11pm. We can be a little flexible around these times and will be offering hot drinks and snacks."
Staff from the Rough Sleeping Team will be on site each night from 9:30pm to 12am.
Rough Sleeping Team staff will then be on call through the night in case of an emergency, and from 7am to pack away and to direct any attendees over the road to Shrewsbury Ark for a breakfast and access to washing facilities and showers.
There will be two security officers from Taybar Security present throughout the night, with a third officer based at Coton Hill House if they are needed in an emergency.
Rough Sleeping Team members will be contacting individuals outside of Shrewsbury each day that SWEP is activated and will offer them a taxi to Shrewsbury so that they can access the night shelter service.
"We will also facilitate them returning to where they came from the next day, ensuring that everyone in Shropshire has the opportunity to access this service.The Met Office alert requires social and healthcare services to take action to protect high-risk groups," said the spokesman.
Temperatures are expected to turn colder across much of the UK late on Wednesday and through Thursday as air from the Arctic spreads south across the country.
The Met Office said that very cold nights are expected with "widespread and potentially severe frosts".
Daytime temperatures are expected to be near or just above freezing.
Wintry showers are also likely to affect some coasts, with the Met Office forecasting they may push into some inland areas at times, bringing a risk of icy patches.
The RAC has advised motorists to check their vehicles are "winter-ready", with properly inflated tyres that have good tread.
Rod Dennis, RAC spokesperson, said: "With temperatures plummeting this week, many drivers might be taken aback by the cold after an exceptionally mild autumn.
"Drivers with older batteries in their cars might also wish to give their vehicle a 20-minute drive before colder conditions arrive to ensure the battery can cope with sub-zero temperatures."
The Met Office has advised people to try and maintain indoor temperatures of at least 18°C, stating that this is particularly relevant for those who are not mobile, have a long-term illness or are 65 or over.
It has also asked people to "look out for friends and family who may be vulnerable to the cold", ensuring they have access to warm food and drinks and are managing to heat their homes adequately.
The Met Office's cold weather alert system operates in England from November 1 to March 31, every year, in association with the UK Health Security Agency (UKHSA).
The system comprises five levels of response based on cold weather thresholds which are designed to trigger an alert when severe cold weather is likely to significantly affect people's health.