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Maintenance and tyres , On the road , Safety and breakdowns · Updated 2026-10-18

Summer heat checklist for your car

Heat is hard on cars and on the people inside them. High temperatures stress the cooling system, the battery, the tyres and the air conditioning, and a parked car can become dangerous within minutes. A short check before the hot season and a few habits during it prevent most summer breakdowns.

Cooling system

The engine cooling system works hardest in summer, especially in traffic jams and on long climbs. Before the season, look at the coolant level in the expansion tank. It should sit between the minimum and maximum marks when the engine is cold. Never open the cap on a hot engine, because the system is under pressure and the liquid can burn you.

If you see sweet-smelling puddles under the car, a temperature gauge that creeps up, or a fan that never seems to run, have a workshop look at it. Our guide to checking coolant and other fluids explains what to look for.

Battery

Many people think batteries fail in winter, but heat damages them too. High temperatures speed up the wear inside the battery, and the weakness often shows up on the first cold morning. If your battery is several years old, ask a workshop to test it before a long summer trip. Keep the terminals clean and tight.

Tyres

Hot asphalt and long motorway runs heat the tyres. A tyre with too little air flexes more and gets hotter, which raises the risk of failure. Check the pressure when the tyres are cold, so before driving or after the car has stood for a few hours, and set it to the value in the manual or on the sticker in the door frame. Look at the tread and the sidewalls for cracks or bulges. See tyre basics for more.

Air conditioning

If the air conditioning blows less cold than last year, the system may be low on refrigerant or the cabin filter may be clogged. Both are workshop jobs. A few habits help the system:

• Open the windows for the first minute in a hot car so the hottest air leaves before you switch on the cooling.
• Use recirculation once the cabin has cooled down.
• Do not set it colder than you need, since it adds load to the engine and uses more fuel.

Oil and other fluids

Heat thins the oil and puts more strain on the engine. Check the oil level on level ground with the engine off for a few minutes, and top up with the grade your manual recommends. If a service is due, do it before the hot season rather than after. Also check the washer fluid, since bugs and dust on the windscreen build up fast in summer.

Never leave anyone in a parked car

A closed car heats up very quickly, even on a mild day and even with a window slightly open. Children, babies and pets can suffer serious harm in a short time. Never leave them alone in the car, not even for a quick errand. If you see a child or an animal locked in a hot car and in distress, call the emergency services.

• Check the back seat before you lock the car.
• Put a bag or a phone on the back seat if you tend to forget.
• Remember that a seat belt buckle or a metal part can be hot enough to burn a child's skin.

Parking in the sun

Park in shade when you can, or use a windscreen sun shade. It keeps the cabin cooler and protects the dashboard from cracking and fading. Leave items such as lighters, sprays, batteries and sunglasses out of the car, because heat can damage or ignite them. Electronic devices and medicines should not stay in a hot car either.

Driving in the heat

Heat makes drivers tired and less alert. Take breaks, drink water, and avoid the hottest hours on long trips when you can. Keep a bottle of water in the car for yourself and for a possible wait in a traffic jam or a breakdown. If the temperature warning appears, do not ignore it. Switch off the air conditioning, turn on the heater at full to draw heat from the engine, and pull over safely if the gauge keeps rising. Read what to do in a breakdown before you need it.

Planning a summer trip

Before a long holiday drive, do the checks above a week or two ahead so there is time to fix anything. Pack water, sun protection, a charged phone and the emergency kit described in the emergency kit checklist. You can estimate the fuel cost of the trip with our trip cost calculator.

What to remember

• Check coolant, oil, tyre pressure and battery before hot weather.
• Have the air conditioning looked at if it cools less than before.
• Never leave children or pets alone in a parked car.
• Park in shade and keep heat-sensitive items out of the car.
• Do not ignore a temperature warning; stop safely and let the engine cool.

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