Is it too early to put the central heating on?
While temperatures drop, homes across the UK are gradually firing up the central heating. But why do some people feel the chill much earlier than others?
Each autumn - or earlier, if summer is particularly disappointing - there's an argument that sunders households up and down the country.
Can we crank up the thermostat yet? Or should we save cash by keeping the heating switched off for as long as possible?
For many people - especially those on low incomes - it's an acute financial conundrum. Energy bills have risen by 28% over the past three years, according to regulator Ofgem, putting pressure on family budgets.
But what often exacerbates these domestic rows is that, for a variety of reasons, some people are simply better at tolerating drops in temperature than others.
Factors such as age, physiology, gender, geography and even hair colour will affect how much each individual feels the cold, say experts.
For some people, however, turning on the heating is a symbolic ritual marking the changing of the seasons - and despite an unusually warm British summer coming to an abrupt halt, many are stubbornly determined to delay it as long as possible.
When temperatures fell on 9 September, novelist John Niven, author of Straight White Male, mentioned to his social media followers that he had switched on his central heating.
The feedback was overwhelmingly disparaging. "The reaction on Twitter was: 'Man up, put a sweater on'," he says.
But perhaps his critics should have been more sympathetic. Scientists agree that some people are physically better equipped than others to endure a drop in the mercury.
For instance, there is a significant gender divide when it comes to feeling the cold, according to Mike Tipton, professor of physiology at the University of Portsmouth,
In low temperatures, he says, the body reacts by diverting blood to the vital organs, and makes the extremities - the head, hands and feet - feel chillier. Oestrogen makes the vessels that shut down blood flow to the skin more sensitive.
As a result, he says, "it tends to be females that complain of cold hands and feet". While a woman's core body temperature may be the same as a man's, her skin is likely to feel cooler.
But there are other physical factors that make a difference, too.
People who are physically fit have better circulation, which makes them feel warmer, says Tipton.
Conversely, he says, excess fat insulates the deep body temperature of overweight individuals. Fatter people also tend to have lower skin temperatures, meaning they are used to the cold.
There are some medical conditions, such as hypothyroidism and Raynaud's syndrome, that cause people to feel colder.
Age is a factor, too. Studies have shown that older people tend to have lower body temperatures, and people's circulation can grow weaker over time.
Genetics can also play a role, scientists believe.
A 2005 study by researchers at Louisville University in Kentucky suggested that people with ginger hair may be more sensitive to the cold than brunettes - somewhat confounding the stereotype of the redhead as a hardy Celt.
Of course, it's not just about how well-equipped or otherwise is your body.
Where people live will make a huge difference, too. Inhabitants of windswept Aberdeen could be forgiven for cranking up their radiators well in advance of those on England's relatively balmy south coast.
It appears that tolerance of low temperatures can be learned. Studies have suggested that the bodies of workers who are regularly exposed to the cold adapt over time to accommodate their environment, according to Tipton.
Similarly, it appears people feel the cold more in the autumn than in March or April.
"There is evidence that there is seasonal adaptation - you get used to the weather," Tipton says. "That works nicely in the spring, but at this time of year where you might see a six or seven degree temperature drop it's not so pleasant."
Also of huge significance is the type of home an individual inhabits. A new-build property, constructed under 21st Century building regulations, will keep the heat in more effectively than a ramshackle period building.
Rambling Victorian houses are notoriously difficult to keep warm, says sustainable design expert Claire Potter. The fashion for lifting up carpets to expose original floorboards means many inhabitants of such buildings will need to switch on the heating sooner.
"People really underestimate how much of a difference a well-insulated house can make," she says.
The UK's ageing housing stock means this is a common problem. Anti-fuel poverty campaigners and environmentalists alike have called for action, but a wide-ranging solution has proved elusive.
In June it was reported that only four people had signed up to the Green Deal, a flagship government policy launched six months earlier to help householders make energy efficiency improvements.
For many, however, delaying putting on the heating is a matter of financial necessity as energy costs soar.
A ComRes survey for BBC Radio 5 live earlier this month found 25% of people had put up with an "unacceptably cold" house during the past year to keep their bills down.
Some 63% of the 1,035 adults interviewed said they had reduced their energy use due to rising costs.
But it isn't just because of poverty or desperation that some people prefer to shiver rather than turn on their radiators. There's a certain type of person who takes pride in keeping the boiler out of action for as long as possible.
Niven says plenty of those who berated him for switching on his heating in early September were far from impoverished. Indeed, the Ayrshire-raised writer recalls once sharing a flat with an old Etonian who as a point of principle refused to countenance putting on the heating before December.
"A lot of public schoolboys grow up in these cold dorms," he adds. "It's a bit of a badge of honour for them."
For his part, Niven associates unheated buildings with the house in which his troubled brother Gary lived before taking his own life in 2010.
Until his electricity was eventually cut off, Gary relied on a pay-as-you-go meter and rationed his heating. "The unit cost was phenomenally high, because of course the poorest people who can't get credit pay the most," says Niven.
As a result, the writer has little patience for those who can afford to turn up their thermostats but boast about putting on extra layers instead.
"If you know you can afford to put the heating on, it becomes this fun game," he says. "But if you're poor, living in an unheated house is just miserable."
Whatever people's reasons for tolerating what others would regard as freezing conditions, another autumn of conflict about what is a comfortable temperature is as inevitable as the changing of the seasons.