Why heat is hard on a car
A car parked in strong sun can become far hotter inside than the air outside. Dark surfaces such as the dashboard and seats absorb heat, and glass traps it. Beyond comfort, high temperatures speed up wear on rubber, plastics, fluids and batteries. A few habits and checks can reduce the damage and make hot days safer.
Safety first: never leave people or pets inside
A parked car can heat up rapidly, even on a mild day and even with a window slightly open. Children, pets and some adults can suffer serious harm or die from heat in a closed car in a short time. Never leave anyone in a parked car, not even briefly. If you see a child or animal locked in a hot car, call local emergency services. Laws and recommended actions differ by place.
Also be careful with items that react to heat. Aerosol cans, lighters, some electronics, and sealed bottles may be damaged or may burst in a very hot cabin. Seat belt buckles and metal parts can burn skin, so check them before buckling children in.
Protecting the cabin
- Park in shade when possible, or choose a garage or covered lot. Consider where the sun will be later in the day, not only when you arrive.
- Use a sunshade in the windshield. Reflective shades can reduce how hot the dashboard becomes, and they help protect it from cracking and fading over the years.
- Use window tint or side shades if they are legal where you live. Rules about tint levels differ between jurisdictions, so check the local regulations.
- Cover steering wheel and seats with a light cloth or towel if surfaces become too hot to touch. Seat covers can also help protect fabric or leather.
- Condition leather and vinyl occasionally, using a product made for them, and avoid leaving soft plastics in direct sun. Regular interior detailing helps keep surfaces from drying out. Where parking in the sun is unavoidable, car covers can also shield the paint and interior.
Cooling a hot cabin quickly
When you return to a hot car:
- Open the doors or windows for a minute or so to let the hottest air escape.
- Start the engine, and set the air conditioning to fresh air with the fan on high at first, then switch to recirculation once the air is cooler.
- Direct the vents toward the roof and body, since cool air falls.
- Use the air conditioning rather than driving with all windows down at high speeds, which can create drag, though at low speeds an open window is fine.
Keep the vents clear and replace the cabin filter on schedule. A clogged filter can reduce airflow and cooling, and you may notice weaker output. If the air conditioning blows warm or smells odd, have it checked, because a leak or a failing part will not fix itself.
Battery and electrical system
People tend to associate dead batteries with winter, but heat is a major cause of battery wear. High temperatures speed up internal chemical reactions that shorten battery life, and a weakened battery often shows its age when the weather later turns cold. In regions with long hot seasons, batteries commonly wear out sooner.
You can reduce the risk by keeping the terminals clean and tight, parking in shade, and having the battery tested if it is more than a few years old. If you notice slow cranking, a dimmer than usual interior light or an unusual smell, have it checked. Knowing how to jump start a car safely is helpful, as is a plan for battery replacement before it fails.
For electric and hybrid cars, heat also affects the traction battery. Cars usually have their own cooling systems, and parking in shade or plugged in with preconditioning may help. Battery health is affected by long-term exposure to extreme temperatures, and your manual is the best guide.
Tires in the heat
Hot pavement and hot air raise tire temperature and pressure. Tires that are underinflated flex more and run hotter, which increases wear and the risk of failure. Check pressures when the tires are cold, such as first thing in the morning or after the car has been parked for a few hours, and inflate to the figure given in the owner’s manual or on the door-jamb label. Do not let air out of hot tires to match the cold figure, because the pressure will fall once they cool.
Inspect sidewalls for cracks or bulges, and look at tread depth. A worn or aging tire is more likely to fail on a long hot drive.
Engine and cooling system
Heat puts extra load on the cooling system, especially in slow traffic, when climbing hills, or when towing. Before hot weather:
- Check the coolant level when the engine is cold. The basics are covered in how engine coolant works.
- Look at hoses for cracks or bulges, and check for leaks under the car.
- Keep an eye on the temperature gauge. If it climbs, turn off the air conditioning, turn on the heater to pull heat from the engine, and pull over safely if it continues to rise. Overheating can seriously damage an engine, and engine overheating needs prompt attention.
- Never open a hot radiator or coolant cap, as pressurized hot fluid can cause severe burns.
Oil also thins when hot, so use the grade your manufacturer specifies, as explained in oil viscosity, and keep the level topped up.
Fuel and other items
Keep the tank reasonably full on hot trips, in case you are delayed. Carry water for everyone in the car, and sunscreen and a hat for emergencies. A good emergency kit for summer includes extra drinking water, a phone charger and a reflective warning triangle if you break down.
Bringing it together
Most of the heat protection comes down to parking smartly, keeping fluids and tires in good shape, and not ignoring early signs of trouble. If you are unsure about the air conditioning, battery or cooling system, a qualified mechanic can check them in a short visit.