A new University of Oxford-led study, published in The Lancet Planetary Health , is the first to link daily temperature data to health-care use and costs across primary and secondary care in England.
Using linked patient records from 4,366,981 people registered at 244 English GP practices between April 2007 and June 2019, the researchers estimate that exposure to average daily temperatures outside a mild reference range (18°C to 21°C) accounts for around 3.0% of recorded health-care costs in their dataset.
Using illustrative budget figures detailed below, this may amount to £3 billion in costs for NHS England and be of the same order of magnitude as spending on dentistry.
As NHS leaders plan for winter pressures and wider service resilience, the study provides new evidence on how temperature-related demand and costs sit across the health system in England.
The UK frequently experiences cold conditions, with days averaging 0°C to 9°C accounting for around 64.4% of the estimated burden, reflecting cumulative increases in NHS use across the winter period. The study also raises a practical concern in extreme cold: when average temperatures fell below 0°C, health-care use declined in the data. This suggests barriers to seeking care in hazardous cold conditions such as snow and black ice.
However, the study also highlights that hot weather, which is becoming more frequent under climate change, also conveys concerning health risks. Very hot days were rare in the study period, which limits precision, but the data reports sharp, same-day surges in parts of the system - including A&E attendances and prescribing - when temperatures are unusually high.
In other words, while cold is linked to a larger cumulative burden on the NHS, heat is linked to sudden spikes that can challenge day-to-day service delivery. Older adults were consistently the most affected group across the findings.
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.'
Illustrative budget impact
The study estimates the share of recorded healthcare costs associated with non-optimal temperature exposure (relative to a reference temperature), rather than producing a national budget total. As an illustration, if a similar proportion applied to NHS England's planned 2023/24 spending on acute services, specialised services and primary medical care (combined £101.4bn), this would correspond to costs on the order of £3bn per year across those categories.
For context, that illustrative figure is above the £2.899bn spent on NHS dentistry reported in DHSC annual accounts for 2022/23, as highlighted by the British Dental Association.
