Some NHS hospitals “have bounced unexpectedly from the recent extreme winter into a summer crisis” due to soaring temperatures across the UK, a leading medic has said.

Dr Nick Scriven, president of the Society for Acute Medicine, said many hospitals had seen a large increase in attendances and admissions due to dehydration, particularly among the elderly.

He said this had added to pressures on emergency departments and acute medical units over recent weeks, derailing attempts to recover ground lost over the winter period.

“We know about the effect cold weather has on health but the recent hot weather has reminded us that heat can be equally as dangerous for people, not only the frail elderly but also those working outside,” Dr Scriven said.

“Hospitals are seeing large numbers of patients, particularly the elderly, requiring hospital treatment for dehydration and it’s effects and that is stretching capacity in some areas.

“The concern is that, certainly in some hospitals, we have bounced unexpectedly from the recent extreme winter into a summer crisis when hospitals will be attempting to get back on track.”

His comments came as Public Health England (PHE) warned that vulnerable people – including the elderly, young children and those with long-term health conditions – were at risk as more hot weather is forecast for the weekend.

Dr Thomas Waite, PHE consultant in health protection, said: “Temperatures are likely to rise on Friday through the weekend and potentially into next week, which may leave older people, young children and those with long-term conditions, including heart and lung diseases, struggling to adapt to the heat.

“So keep an eye on friends and family who may be at risk.

“To beat the heat, try to keep out the sun from 11am to 3pm, walk in the shade if you can, apply sunscreen and wear a hat if you have to go out in the heat. Also try to carry water with you when travelling.”

Most of the country is expected to enjoy warm and dry conditions this weekend, with the hot, sunny weather predicted to last into next week when temperatures could reach 31C.

The Met Office has said Britain could see a record-breaking summer if temperatures stay above average.

Between June 1 and July 16, average daily maximum temperatures across the country have been 20.9C (69.6F), compared with 21C (69.8F) for the hottest summer on record, 1976.

Even if the rest of the summer is average, 2018 will still rank in the 10 warmest summers on record and if the UK continues to see above average temperatures, “it could well be record breaking”, the Met Office said.

Dr Scriven added: “Although everyone is at risk during periods of extreme heat, the elderly are a particular concern and, wherever possible, people should do what they can to look out for their relatives and neighbours.

“Just keeping check on them, ensuring they are cool and well hydrated and have people they can call on can all help to avoid hospital admission in this vulnerable group.”

NHS England figures show accident and emergency departments faced their second busiest month ever in June.

There were 2,091,318 A&E attendances last month, while the highest ever was in May with 2,161,779.