A blistering heatwave this summer led to a spike in deaths, new figures suggest.
The elderly, infants and people who suffer from a number of pre-existing health conditions are at particular risk during a heatwave.
New provisional figures from the Office for National Statistics (ONS) show that the soaring temperatures in summer 2016 led to an "unusual peak in mortality" on July 19.
On this day, when temperatures peaked at 33.5C (92.3F), there were 1,661 deaths recorded in England and Wales.
This compared with a five-year average of 1,267, the ONS said.
The authors of the ONS report wrote: "There was an unusual peak in mortality around 19 July 2016.
"Trends in provisional temperature data from this period show that there were higher than average temperatures around 19 July 2016, which may explain the peak in mortality at this time."
Met Office spokesman Grahame Madge said: "From the 17th (of July), conditions in south-east England started to turn very warm, and by the 18th conditions across the UK were dry, hot and sunny.
"On the 19th, it was even hotter, with temperatures widely above 30C.
"Brize Norton in Oxfordshire, with 33.5C, recorded the highest UK July 2016 temperature on the 19th.
"The hot spell ended with a thundery breakdown in the South East and parts of northern England."
The figures also reveal that the number of "excess winter deaths" almost halved during the winter of 2015/16.
There was an "uncommonly high" number of winter deaths the previous year, with 43,850 excess winter deaths recorded by officials in 2014/15.
But during the winter of 2015/16 - between December last year and March - there were around 24,300 additional deaths compared with the rest of the year, figures show.
The ONS said this number falls in line with the long-term average number of excess winter deaths.
The 2015/16 flu season appeared to affect younger people rather than the elderly which led to a fall in the number of older people who died during this period, the ONS said.
A third of 2015/16 excess winter deaths were caused by respiratory diseases.
"One of the key factors behind the lower excess mortality this winter was a fall in the number of deaths among the elderly," said ONS statistician Dr Anne Campbell.
"This was mainly due to the most prevalent strain of the flu virus impacting younger people rather older people, who are more at risk."
Experts said the figures should act as a prompt for people at risk to take particular care as the winter draws in.
Commenting on the figures, Caroline Abrahams, charity director at Age UK, said: "The 2014/15 figures were among the worst seen in modern times so we are relieved these new statistics for 2015/16 are 'a return to average trends', as the ONS puts it.
"Nonetheless, the estimated 24,300 excess deaths last winter - 20,800 among the over-65s - are still a grim reminder of the grave risks the winter poses for older people, and of the need for them to wrap up warm when they go outside and to get their flu jab to help keep them safe.
"It is shameful that Britain has one of the worst winter death rates in Europe, even compared to other much colder countries, and we need to up our game as a nation to bring these figures down.
"Tackling poor-quality, cold housing is an urgent priority and, as well as making life better for older people, this would also support the NHS and social care services since cold-related illness cost them around £1.35 billion every year - a sum they can ill afford.
"With winter around the corner, we urge older people to ensure they're doing everything possible to protect themselves against the cold weather. Anyone who is concerned about staying warm and healthy this winter should call us free of charge on 0800 169 6565 or check our website www.ageuk.org.uk."
Dr Mike Knapton, associate medical director at the British Heart Foundation, said: "The figures paint a worrying picture for winter in the UK, showing a spike in deaths from heart disease at this time of year.
"We know that, as you get colder, your blood vessels constrict and the blood thickens increasing your risk of heart disease and stroke.
"People with chronic heart disease are around 11 times more likely to die if they develop flu compared to healthy individuals; therefore, it is particularly important that people living with heart conditions are well-prepared, keep warm during the winter and have a flu jab."