Cold weather and rising heat are placing a significant and year-round strain on NHS England, with temperature-related illness accounting for around 3% of spending across primary and
secondary care, according to a major new study.
Research led by the University of Oxford and published in The Lancet Planetary Health is the first to link daily temperature data with health-care use and costs across the English NHS. Drawing on 4.37 million patient records, the study shows that winter cold drives the bulk of cumulative demand, while very hot days trigger sharp, same-day surges that can stretch services.
The analysis covers 4,366,981 patients registered at 244 GP practices in England between April 2007 and June 2019. Researchers estimate that exposure to temperatures outside a mild range of 18°C to 21°C accounts for about 3% of recorded health-care costs in their dataset.
Cold days were responsible for nearly two-thirds of the burden. Days averaging between 0°C and 9°C accounted for around 64% of estimated costs, reflecting steady increases in GP visits, hospital care and prescribing throughout the winter months. However, the study also identified a drop in health-care use when temperatures fell below freezing, suggesting that hazardous conditions such as snow and black ice may prevent some patients from accessing care.
Hot weather, while less frequent during the study period, posed a different challenge. Unusually high temperatures were linked to sudden spikes in demand on the same day, particularly in A&E attendances and medication prescribing. Although the overall cumulative cost of heat was lower than that of cold, these abrupt surges can put immediate pressure on frontline services.
Older adults were consistently the most affected group across both cold and hot conditions.
Dr Patrick Fahr, Senior Health Economist at the Nuffield Department of Primary Health Care Sciences, University of Oxford, and a lead author of the study, said:
‘Temperature affects the NHS every day, but until now nobody knew how costly this was. Three percent is both a small and a large figure, because these costs are concentrated on cold and hot days only when demand is spiking. Historically, the winter season has been and remains associated with additional health risks, which occur routinely each year, however heatwaves are emerging as a new challenge.
‘In the data, heat tends to be associated with short, same day increases in demand and pressure on services, requiring a rapid response. Overall, the practical implication is that planning for temperature-related variation in service use is a year-round issue. Vulnerable people, such as older adults, can be particularly at risk.’
The study does not calculate a definitive national cost. However, applying the same proportion to NHS England’s planned £101.4bn spending on acute, specialised and primary medical care in 2023/24 would suggest temperature-related costs of around £3bn a year. That figure is of a similar order of magnitude to NHS spending on dentistry.
As NHS leaders plan for winter pressures and long-term resilience, the authors say the findings underline the need for year-round planning to manage the health impacts of both cold and heat in a changing climate.