Is it safe to drive in a heatwave? In short, yes it is, so long as you take the proper precautions – which doesn't just mean cranking up the air-conditioning and hoping for the best. In this short guide, CarGurus offers a few simple tips for helping you, your passengers and your car cope with driving in sweltering conditions.
Is it Safe to Drive in a Heatwave?
- Check Your Car's Coolant
- Check Your Car's Oil
- Windscreen Washer and Windscreen Wipers
- Air-Conditioning
- Tyres
- Pets
- Sun Shades
- Check the Forecast
- When the Rain Arrives
- Consider EV Range
Check Your Car's Coolant
The primary function of your car’s cooling system is to prevent your engine from overheating. The coolant system is sealed so it shouldn’t need topping up between services. Even so it is worth locating the coolant system’s header tank or expansion tank, which looks like a plastic ball with ‘Min’ and ‘Max’ markers. If the level of coolant within is below the ‘Min’ marker ask a garage to top up and inspect the system for leaks. Alternatively you could replenish the coolant (either with pre-mixed coolant or an antifreeze which you then top up with water), and keep a close eye on coolant levels. To avoid scalding yourself, only ever open the header tank when the engine is cool. For more details, see our full guide about how to check your engine’s coolant.
Check Your Car's Oil
Oil doesn’t only lubricate an engine’s components, but also helps with heat dissipation. To check the oil level, pull out the dipstick and look for a line of oil between the ‘Min’ and ‘Max’ markers. If the level is below ‘Min’, remove the oil cap and pour in the recommended oil a little at a time. Leave a few seconds for it to drain into the engine, then check the level on the dipstick again. Unlike coolant, it is not unusual for a car to use a bit of oil between services, which is why it’s important to check it every couple of weeks and before any long journeys. For more details, see our full guide about how to check your car’s oil.
Windscreen Washer and Windscreen Wipers
Another task worth performing when the bonnet is open is to top up the windscreen washer fluid. In an emergency you can just use water for this, but it will be much more effective when mixed with proper screen wash fluid, which is available from car accessory stores or online. Mixed to the recommended concentration, this will also stop the washer fluid freezing in the winter months. Worn wipers will struggle to clear dirt and bugs, so consider renewing these too.
Air-Conditioning
If your car’s air-conditioning is losing its effectiveness, then take it to a specialist to be serviced and regassed (note, this is not a DIY job). It is recommended this is done every two to three years to keep the system operating at its optimum efficiency, and running the air-con on a regular basis will also help with keeping it in prime condition. On older cars it is also worth considering having the air-conditioning system cleaned (again a job for a specialist) to remove dirt and bacteria. As an aside, don’t be too alarmed if you see a small puddle of liquid underneath your car after a long drive on a hot day – it is most likely simply condensed water from the air-conditioning.
Tyres
Ensuring your car's tyres are at the recommended pressures is good practice at any time of year, but in the summer the high temperatures can increase the likelihood of problems. This is important, because if you’re unlucky enough to suffer a blowout, it can lead to bigger problems. That’s particularly the case for tyres that are under-inflated, worn or simply old. Remember to check your spare tyre (if applicable) is in good condition and at the correct tyre pressure, too. If you're concerned about the condition of your car's tyres, visit our full guide about how to check tyre depths, tread and condition.
Pets
It should go without saying that it is incredibly dangerous to leave pets in an unattended vehicle on a hot day. Data from the RSPCA shows that if the temperature outside of a car is 22C it can get to 47C inside a car within the space of an hour. It warns that parking in the shade or with the windows slightly open can still be very dangerous, and encourages anybody who sees a dog in distress in a hot car to dial 999.
Sun Shades
It might seem old-fashioned in this fully connected age, but a sun shade is an inexpensive and effective way to keep a car’s interior cool when you’re parked. That includes protecting surfaces such as the steering wheel, gear-lever and seats from direct sunlight. They are also a great way of keeping the sun off kids in the back of a car.
Check the Forecast
Make sure that you know when extreme temperatures are coming. We don’t get excessively hot weather too often in the UK, so it’s usually well publicised by the national media when extreme heat does happen, so remember to check the latest news. The Met Office doesn’t always get things right, however, so even when hot weather is not expected, it’s a good idea for motorists to keep an emergency kit of hot weather precautions in their car during the summer months, especially if they’re planning a long road trip. Pack plenty of water (and make sure you and your passengers always have a bottle of water to hand), and remember to bring a pair of sunglasses, sun cream, a mobile phone and your in-car charger. A first aid kit is always a good idea, and remember to include any hay fever medication you might require, avoiding anything that makes you feel drowsy. Plan ahead on long journeys so that you have time for regular breaks, and avoid travelling during rush hour if at all possible. If you do get stuck in a traffic jam, keep an eye on the engine’s temperature gauge to ensure the car doesn’t overheat.
When the Rain Arrives
After a prolonged dry spell the roads will be coated in dust, dirt, oil and rubber that, when water is applied, can become incredibly slippery. That is why conditions can be particularly tricky after the first rain has fallen following a heatwave. It is thus sensible to keep your speed down and leave more room to brake than you normally would.
Consider EV Range
Some independent studies have shown that the range of some electric cars can suffer in very hot weather. One of the reasons for this is that when a car has been parked in the sun, cooling its cabin can use a lot of energy, which in an EV has the potential to also deplete its overall range. Therefore, if it’s possible to pre-cool the cabin while the car is still plugged in this can help to minimise any drop in range, as well as providing a cool oasis when passengers climb aboard.