Heatwaves, Fuel Moisture, and Rising Wildfire Risk
- Rob Beeson
- Sep 1
- 2 min read
A new UK study has shown how extreme heatwaves can dramatically increase the risk of severe wildfires on heath and peatland landscapes. Researchers monitored more than 5,800 samples of heather and soil moisture across 43 sites between 2021-2023, including during the record July 2022 heatwave when UK temperatures exceeded 40°C.
Under normal conditions, different parts of the moor hold moisture differently. Live heather usually stays damp in summer, while dead heather and surface soils respond more to short-term weather, and deep organic soils are influenced by landscape features such as soil type and elevation. This seasonal pattern helps limit large fires.
But during the 2022 heatwave, these natural differences broke down. All fuels - live heather, dead stems, and organic soils - dried out at the same time, creating unprecedented fire conditions. Dead heather moisture dropped to just 4% (from around 18% the previous summer), and the chance of ignition jumped from under 11% to 87%.
Simulations showed fires spreading more than four times faster than normal July conditions, with flame lengths exceeding 1.5 metres - beyond what fire crews can tackle safely with hand tools.
The findings highlight a growing threat. With heatwaves predicted to become longer and more frequent, moorland landscapes will face greater risk of uncontrollable wildfires unless fuel is managed effectively.
Takeaway: For those who live and work on moorland, this research reinforces the importance of active land management - such as controlled burning and grazing - to keep fuel loads in check and protect both people and wildlife.
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