A study led by researchers at the University of Oxford estimates that around 3% of NHS England’s primary and secondary care costs are associated with days of unusually cold or hot weather.
“Temperature affects the NHS every day, but until now nobody knew how costly this was,” said lead researcher of the study Dr Patrick Fahr, Senior Health Economist at the Nuffield Department of Primary Health Care Sciences, University of Oxford.
Published in The Lancet Planetary Health, the research analysed 4.37 million anonymised patient records from 244 GP practices across England between April 2007 and June 2019, linking daily temperature data to healthcare activity and costs.
The researchers found that temperatures outside a reference range of 18°C to 21°C were associated with increased use of NHS services.
When extrapolated to recent NHS budgets, this equates to an estimated £3bn per year.
Analysis of 4.37 million patient records in England finds resources asymmetrically impacted by winter cold and summer heat, with about 64% linked to common cold days while very hot days drive sharp same-day demand surges.
Cold weather drives the highest weather-related costs
The study showed that cold temperatures accounted for the majority of weather-related costs, with healthcare use increasing most when average daily temperatures were between 0°C and 9°C.
Primary care consultations, hospital admissions and prescription volumes all rose during colder periods, reflecting familiar seasonal pressures on the health system.
However, at temperatures below freezing, overall healthcare use declined.
The authors suggest this may reflect reduced ability to travel or access services during extreme weather, rather than reduced clinical need.
Heat linked to short-term spikes in healthcare use
Hot weather was also associated with increased NHS activity, though its impact differed from cold exposure.
Higher temperatures were linked to immediate same-day increases in healthcare use, particularly in emergency care and prescribing.
While extreme heat events were less common during the study period, the researchers note that the sharp increases in demand they trigger present a different operational challenge for services.
Population impact
Across both hot and cold conditions, older adults experienced the greatest increase in healthcare use, underlining the vulnerability of ageing populations to temperature extremes.
Dr Fahr said the findings demonstrate how even relatively small percentage increases can have a significant impact when demand is concentrated on specific days.
The researchers conclude that temperature variation should be considered more explicitly in healthcare planning, particularly as climate change increases the frequency and intensity of extreme weather events.