Driving in Extreme Heat: What Every UK Motorist Needs to Know

The UK is no stranger to the occasional heatwave, but when temperatures push into the mid-30s and beyond, our roads become a very different and far more demanding environment. During recent extreme heat events, the RAC reported a 20% surge in breakdown callouts compared to a typical day — and warned that breaking down in such conditions can be genuinely life-threatening if you’re not properly prepared.

At CCM Garages, we want to help you understand exactly how rising temperatures affect your vehicle — and what you can do to stay safe on the road.

Why Extreme Heat Is Hard on Your Vehicle

Cars are engineered to operate within a broad range of temperatures, but sustained extreme heat pushes components to their limits. Many of the systems working hardest to keep you moving — your engine, cooling system, tyres, and battery — are also the most vulnerable when the mercury rises.

Understanding how your car behaves at different temperature thresholds can help you spot problems early and avoid a breakdown.

Temperature Bracket Guide: Vehicle Risk & Response

Up to 25°C — Low Risk Normal operation, though tyre pressures may begin to rise slightly. Check tyre pressures before long journeys.

25–30°C — Moderate Risk The air conditioning works harder, and coolant temperature can edge up on slower roads. Ensure coolant is topped up and avoid heavy traffic where possible.

30–35°C — High Risk Overheating risk increases noticeably. The A/C is under greater strain, and oil degrades faster under load. Check coolant and oil before driving, avoid prolonged idling, and keep an eye on your dashboard gauges.

35°C+ — Very High Risk Serious overheating becomes a real possibility, alongside the risk of tyre blowouts, battery stress, and potential brake fade. Only drive if essential, carry water, plan rest stops, and act immediately if any warning lights appear.

The Key Risks — Explained

Overheating Engine

Your engine relies on coolant to regulate its temperature. In extreme heat, especially in slow-moving traffic, the cooling system has to work much harder. If coolant levels are low or the system has a fault, your engine can overheat rapidly. Watch for the temperature gauge climbing toward the red, steam from the bonnet, or a warning light on your dashboard. If any of these occur, pull over safely as soon as possible, turn off the engine, and do not attempt to open the bonnet immediately.

Tyre Blowouts

Heat causes the air inside your tyres to expand. Tyres that are already slightly overinflated — or that have worn tread — are at a much higher risk of a blowout when road surfaces become extremely hot. Before driving in high temperatures, check your tyre pressures when the tyres are cold, and inspect tread depth. The legal minimum is 1.6mm, but we recommend replacing tyres at 3mm for safety.

Battery Strain

While we often associate flat batteries with cold winter mornings, heat is actually equally damaging over time. High temperatures accelerate the chemical reactions inside a battery, which can shorten its lifespan and increase the risk of failure. If your battery is more than three years old, it’s worth having it tested before a hot spell takes it by surprise.

Air Conditioning Load

Running your air conditioning places an additional load on your engine, which in turn generates more heat. On long journeys in high temperatures, this can contribute to engine strain. Keep cabin temperatures comfortable rather than arctic — a modest, consistent cool is easier on the system than running the A/C at maximum output continuously.

Brake Fade

Repeated heavy braking on long downhill stretches in high heat can cause brake fade — a temporary reduction in braking efficiency caused by overheated brake components. This is more likely if your brake fluid is old and has absorbed moisture. We recommend having your brake fluid tested if it hasn’t been changed in the last two years.

A Word on Idling — It’s Not Worth the Risk

When it’s hot, it can be tempting to sit in your parked car with the engine running and the air conditioning on. However, this is not only harmful to air quality — it can also land you with a fine. Idling with the engine running is an offence under UK emissions regulations, and fines typically start at £40, doubling to £80 if issued by a civil enforcement officer. Some councils apply higher penalties still.

If you need to cool down, park in the shade, open the windows, and let the car’s natural ventilation do the work before setting off.

Before You Drive in the Heat: A Quick Checklist

• Check coolant level — top up if needed (only when the engine is cold)

• Check engine oil — low oil in high heat accelerates engine wear

• Inspect tyre pressures and tread depth

• Test that your air conditioning is working effectively

• Ensure you have water in the car — for you and, if applicable, pets

• Check your battery condition if it’s older than three years

• Plan your route to avoid heavy traffic where possible

• Only travel if your journey is necessary — in red weather warnings, the advice is to avoid driving altogether

Get Your Vehicle Summer-Ready with CCM Garages

Don’t wait for a warning light to tell you something is wrong. A pre-summer vehicle check with CCM Garages covers all the key systems — coolant, oil, tyres, brakes, battery, and air conditioning — so you can drive with confidence whatever the weather. Book your appointment today.

Extreme heat is unpredictable, but a well-maintained vehicle gives you the best possible chance of handling it safely. Stay cool, plan ahead, and if in doubt — stay off the road.

For more information, visit **ccmhelp.co.uk** or give our friendly teams a call.

CCM Ewhurst: 01483 278166

CCM Cranleigh: 01483 278060

CCM Gatwick: 01293 871430

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