Motorists in the United Kingdom are being advised to prepare their vehicles for extreme heat as a rare red weather warning for extreme heat has been issued for parts of the country, with temperatures potentially reaching 40C. The UK Health Security Agency has issued a 'danger-to-life' alert for six regions. This intense heat is expected to cause significant travel disruption on both rail networks and roads.

Breakdown services are reporting an increase in callouts. The RAC states that callouts have risen by approximately 20% compared to a typical Monday in late June. The AA has cautioned drivers to expect to see gritters deployed on roads to manage the heat's impact.

Vehicle Preparation and Common Issues

Experts highlight several common causes of heatwave-related vehicle breakdowns. RAC patrolman Jack Halstead identified batteries as a primary concern, noting that older batteries, particularly those four to five years old, are more prone to failure. Signs of a failing battery include slow starting, dimming dashboard lights, or a warning sign on the dashboard. Short journeys and the use of multiple devices can further drain a battery.

Tyre blowouts, caused by expanding air in the heat, are another significant risk. Halstead advises drivers to check tyres for cracking and ensure they are inflated to the correct levels as specified in the vehicle handbook. He also warns that tyre pressures increase with temperature, so checking them mid-journey can yield artificially high readings. Maintaining a tread depth above the legal minimum of 1.6mm is also crucial.

Punctures are also common in summer, especially when vehicles are heavily loaded. Many newer cars come with inflation repair kits instead of spare wheels, which are effective only for punctures up to 6mm. Drivers are advised to familiarize themselves with these kits or contact their breakdown assistance provider.

Strain on a car's clutch can occur during traffic jams, which are common during heatwave-related disruptions. Warning signs include a heavy or gritty pedal, a high clutch bite point, or clutch slipping, particularly noticeable during acceleration.

The alternator, responsible for charging the battery and supplying power to electrical systems, can struggle under the increased demand of hotter weather and additional electrical devices. A flashing red battery warning light or a battery warning symbol on the dashboard can indicate an alternator issue.

The AA notes that extreme hot weather places additional strain on vehicles, especially older models or those not recently serviced. Cooling systems are under more pressure, making it important to monitor coolant levels and watch for signs of overheating. Tyre pressures and oil levels should also be checked, and drivers should be vigilant for warning lights, unusual smells, steam from the engine, or rising temperature gauges.

Road Surface Concerns and Driver Safety

Road surfaces can reach temperatures of up to 50C during heatwaves, potentially causing asphalt to soften. Authorities may deploy gritters, typically used for winter conditions, to spread a fine layer of crushed stone or granite dust. This material provides protection from the sun and improves tyre grip. Drivers are warned that softened road surfaces can become tacky or uneven, affecting braking, steering, and grip, and may also throw up loose material. It is recommended to slow down, avoid harsh braking or steering, and maintain extra distance from the vehicle ahead.

Tips for Staying Cool and Prepared

To keep car interiors cool, parking in the shade is recommended. Covering seats, particularly leather ones, with a blanket or jacket can prevent them from becoming excessively hot. Drivers are urged to carry ample water and soft drinks, ideally in an insulated container. A cool box with cold beverages and snacks can be useful if caught in traffic or during a breakdown. Spare hats, umbrellas, and sun cream are also advised for personal protection.

Ensuring a mobile phone is fully charged before journeys is crucial for emergencies. Downloading and logging into a breakdown provider's smartphone app can aid in locating the vehicle if a fault occurs. Keeping a spare pair of sunglasses in the car is also a practical tip.

The AA is reminding the public that parked vehicles can become dangerously hot very quickly, and children, vulnerable passengers, and pets should never be left unattended, even for brief periods.

Optimizing Air Conditioning Use

When using air conditioning in high temperatures, experts advise against immediately setting it to maximum. Opening doors for a minute or two before driving can help ventilate the car and release hot air. Using the air recirculation button initially allows the system to cool the existing air more efficiently, rather than working harder to cool incoming hot air from outside. After a few minutes, switching to drawing fresh air from outside, which is filtered and cooled, can maintain a comfortable cabin temperature while reducing strain on the vehicle's electrical system and potentially preventing breakdowns. This method can also extend the time between air conditioning re-gas or recharge services. For electric vehicle owners, using smartphone-linked cabin pre-conditioning functions can ensure a cooler interior upon entry without significant battery drain.