The Met Office says temperatures are expected to climb to at least 39°C at the peak of the heatwave, with a chance that this could be exceeded in places. The UK Health Security Agency has also issued red heat-health alerts for six English regions, warning of serious impacts on health and social care services, transport systems, supply chains and businesses.
For hauliers running long-distance trunking, urban distribution or temperature-controlled freight, the forecast is more than a weather inconvenience. High temperatures can affect vehicle reliability, driver concentration, route planning and delivery commitments.
What breaks down and why
High ambient temperatures put vehicle systems under sustained stress, particularly on routes involving motorway running at speed or urban stop-start work.
Tyres are one of the main concerns. Hot weather increases tyre pressure, while road surfaces can become far hotter than the air temperature in direct sun. Underinflated, damaged or worn tyres are therefore a greater risk during a heatwave, especially on heavily loaded vehicles.
Cooling systems also come under greater pressure when ambient temperatures are high and vehicles are stuck in traffic. Coolant levels, hose condition and radiator cleanliness become more critical. A slow coolant leak that causes no immediate problem in winter can become an overheating risk in summer.
Batteries can also be vulnerable in hot weather, as high temperatures accelerate degradation in lead-acid batteries. Fleet operators running older vehicles should pay particular attention to battery condition before the heat peaks.
Air conditioning failure is not just a comfort issue. In high temperatures, a working cab climate system becomes part of driver welfare, particularly for drivers spending long hours on the road or waiting at collection and delivery points.
The RAC has warned of an early summer surge in breakdowns during the hot spell, saying demand for roadside help could rise by around 10% compared with a normal mid-June period. It said overheating engines and tyre blowouts were expected to be among the leading problems.
Driver welfare: what operators need to manage
There is no statutory maximum workplace temperature in UK law. However, the Health and Safety Executive has reminded employers that they must assess risks to workers’ health and safety, including risks from extreme weather such as heatwaves.
HSE says heat is classed as a hazard and should be treated like other workplace hazards. It advises employers to discuss with workers what changes may be needed to manage the risk, including practical measures such as ventilation, rest breaks and access to drinking water.
For hauliers, this means checking not only depots and warehouses, but also the working conditions of drivers on the road. Schedules that may be workable in normal weather can become unrealistic during extreme heat, especially if drivers are delayed in traffic or have to wait roadside after a breakdown.
Andrew Tavener, Head of Fleet Marketing EMEA at Descartes, said extreme weather was increasingly becoming part of normal operating conditions for logistics businesses.
“Dealing with extreme weather is becoming part of the norm for logistics operators in the UK. And with the temperature rising again over the coming week, there’s a very real risk that some businesses could fall behind on their last-mile delivery schedules,” he said.
Tavener said driver safety and wellbeing should be the first priority, including realistic schedules, clear guidance, regular breaks and the ability for drivers to raise concerns if conditions become unsafe.
“That means giving drivers realistic schedules, clear guidance, regular breaks and the ability to raise concerns if conditions become unsafe,” he added.
Operational planning under heat
Route planning becomes more important in extreme heat, not only for efficiency but also for driver protection and vehicle reliability. Avoiding known congestion points during the hottest part of the day can reduce time spent idling in traffic and lower exposure for both drivers and vehicles.
Royal Mail has warned customers that services may need to be adjusted or paused where extreme heat makes access unsafe, a sign that last-mile operators with residential delivery commitments may also need contingency plans.
Tavener said delivery scheduling and route optimisation software could help companies keep workloads manageable, while order tracking and automated notifications can keep customers informed if delays occur.
Vehicle safety inspection apps also have a role in extreme weather, he added, by allowing drivers to record and report daily vehicle checks to the depot.
“During extreme heat, this becomes even more important, as tyres, brakes and cooling systems come under additional strain,” Tavener said.
For temperature-controlled freight, chilled, frozen and pharmaceutical loads add another layer of risk. Operators should check refrigeration unit service records and make sure drivers know what to do if a reefer unit fails en route.
Tyres, coolant and drivers: the heatwave checklist
Before vehicles leave the yard, operators should ensure daily walkaround checks give particular attention to tyres, coolant levels, brakes and air conditioning.
Fleet managers should also confirm that cab air conditioning is working, review schedules where possible to reduce driver exposure during the hottest hours, and make sure drivers have enough water and clear instructions on what to do if they feel unwell.
Drivers should be reminded that heat fatigue can impair reaction time and concentration. Symptoms such as dizziness, confusion, severe thirst, headache, nausea or stopping sweating despite the heat should be treated seriously.
The red heat-health alert is in force in six English regions from 1am on Wednesday 24 June until 11pm on Thursday 25 June. The Met Office says conditions should become less hot by Friday, although high temperatures are still expected in eastern areas.
