What you need to know about driving in hot weather

How hot weather affects your car 

Battery

Heat can put additional strain on everything from your tyres to your car battery. If you haven’t booked your car in for a service for a while, Smith recommends doing so before you hit the road. 

“High temperatures can evaporate your battery's vital liquids and weaken its charge,” he says.

“What's more, hot temperatures can speed up the corrosion process. Corrosion will irreversibly damage the internal structure of the battery.”

This damage is even more pronounced if the battery is parched so, if yours has caps, check the level and top up as necessary. 

Tyres

Excess heat from the sun can also wear out your tyres. “As the temperature rises, the air pressure in your tyres increases,” Smith explains. “Over-inflation of tires can interfere with braking and cause your tire to wear out prematurely.”

Under-inflated tyres are also problematic because they have more flex. This can contribute to heat build-up, making them more likely to fail. 

Whether travelling in hot weather or not, Smith says it’s always a good idea to check your trye pressure before any long drive as over- or under-inflated tyres will not only wear out faster but can also impact your car’s fuel efficiency and on-road performance. 

“While you’re at it, don’t forget to check the tread depth,” he says. “On every tyre there is a small bar next to the letters TWI (tread wear indicator). If your tyres are worn to this bar, its’ time to replace them.”

On really hot days, Smith says the road surface can also become soft and sticky, particularly if it has been recently sealed. "Be aware that not only can the heat cause your tyre pressure to change, it can also change the road surface on which you’re driving so try to avoid any potholes or cracks.”

Always check your tyre pressure before heading off on a road trip. Photo: Getty. 

How to prepare for driving in hot weather

Get a service 

If it’s been a while between auto services, ensuring your car is in tip-top shape is one the best things you can do to prepare ahead of any road trip, but especially a summer one. Hot weather can lead to increased mechanical stress, placing additional strain not just on your battery and tyres, but on your engine and other components, such as belts and hoses, too. “Maintaining your car is one of the most important things you can do to keep heat-related problems at bay,” Smith days. 

Regular servicing will also ensure your car isn’t thirsty. Adequate coolant, engine oil and brake, air conditioning, power steering and wiper fluids are critical to the health and safety of your vehicle. 

“If your car doesn’t have enough coolant, for example, it is possible the engine could overheat, which could cause significant damage,” Smith says. “And making sure your wiper fluid is topped up will ensure you can keep your windscreen clean, particularly when driving along dusty roads.”

And if you turn your car air conditioning on and you get that musty smell, he says you may need an anti-bacterial service. 

Carry an emergency kit

While there’s never an ideal time for your car to breakdown, it’s important to always be prepared. Do you have what you need in your car in case of a breakdown, such as jumper cables, a flashlight or even a jerry can? An emergency kit is something you should carry in your car year-round, but if you’re planning a hot-weather road trip, be sure you’ve got extra bottles of water to keep you hydrated, as well as snacks and a phone charger. “If you’re travelling long distances in extreme temperatures, it’s worth carrying extra coolant, gloves and a rag/towel in case you need to pop the hood.” Smith says. 

He says it’s also important to check that your Emergency Roadside Assistance is up to date so that you’re covered in case things go awry on the road. 

Take breaks

Heat can also impact our ability to drive and concentrate so try to plan for regular stops. “An increase in temperature can effect a driver’s ability to react to potentially dangerous situations,” Smith says. “And it is often acknowledged that drivers are more likely to be involved in a motor vehicle accident when they are tired, angry, flustered, uncomfortable or exhausted.”

If you sense yourself getting fatigued or becoming drowsy, pull over for a power nap, stop for lunch or just get out and stretch your legs. This will help to break up the drive and keep you alert behind the wheel. 

Never leave kids or pets alone in the car

Leaving a child in a hot car – even briefly – can be fatal. On a hot day, temperatures inside a car quickly climb, sometimes soaring 20-30 degrees higher than outside air. In Victoria, it is illegal to leave a child unattended in a car, with penalties including a hefty fine ($4,030), prison or both. 

It is also an offense to leave an animal unattended inside a vehicle for more than 10 minutes when the outside temperature is 28 degrees Celsius or above. For doing so, drivers could face a fine of $3304.40.  

Smoke, a hot hood or a loud ticking noise could be signs your car is overheating. Photo: Getty.

What to do if your car is overheating

Modern cars are equipped with various technologies designed to keep them running at the optimum temperature in any condition. But despite sophisticated cooling systems, heat sensors and computer-controlled fans, overheating can still happen. If you see the temperature gauge light come on, take note, Smith says. “Pull over as soon as it is safe to do so and turn off your engine,” he says. “Sit tight and, if you don't have roadside assistance, be patient; it will take at least 15 minutes for the engine to cool.”

If you have coolant, and you’ve waited at least 15 minutes, once the bonnet is cool to touch you can try popping the hood and topping it up. Smith says to bear in mind that there may be some built-up pressure from the coolant expanding in the heat. “If you turn on the engine and the gauge is back to normal, you can continue driving. But be cautious and pay attention to the temperature gauge. If possible, drive it straight to your nearest mechanic or service station to address the overheating issue.”

And though it might sound counterintuitive, if you think your car might be struggling, Smith says sometimes turning off the air conditioner and cranking up the heater can prevent it from overheating. “This can help to draw heat away from the engine and into the passenger compartment, reducing strain on the engine’s cooling systems,” he says. 

Other signs of your car overheating include the presence of smoke or steam coming out from under your hood, a hood that is hot to the touch, a loud ticking noise and coolant on the ground. 

Tips for keeping your car cool in hot weather

• Park your car in the shade. “But don’t park under blooming trees as they can drop sap and other juices,” he says. “This can damage the car’s paintwork.” He also says to avoid parking in long grass as this can pose a fire risk. 
• Don’t leave anything sitting on the dashboard. “It could melt in extreme heat damaging the dashboard,” he says.
• Use a sunshade on the windscreen. “This will help to keep the heat out and make the internal temperatures more comfortable when you get in.”
• Check your coolant and oil levels weekly. “This will ensure your car is running optimally at all times and reduce any potential engine strain.”

The information provided is general advice only. Before making any decisions please consider your own circumstances and the Product Disclosure Statement and Target Market Determinations. For copies, visit racv.com.au. As distributor, RACV Insurance Services Pty Ltd AFS Licence No. 230039 receives commission for each policy sold or renewed. Product(s) issued by Insurance Manufacturers of Australia ABN 93 004 208 084 AFS Licence No. 227678.