How High is the Temperature Inside a Car in Summer?

[DeJace]

When a car is parked outdoors in 40℃ high temperature and exposed to the sun for a long time, the temperature inside the car can exceed 70 degrees, reaching up to 90 degrees at maximum. In summer, the outdoor temperature in most areas can reach around 40℃. However, most car interiors are black, which absorbs heat more easily, and the car is a closed environment, so the temperature will rise sharply over time. Here are some methods to deal with high temperatures inside the car: 1. Physical cooling: Mix alcohol and water in a ratio of one to ten, put it in a small spray bottle, and keep it in the car for preparation. Open the car door, spray lightly a few times, then close the door, and the temperature will drop in two to three minutes. 2. Open three sides for ventilation. 3. Lower the window on the passenger side and repeatedly open and close the driver's side door, which can also effectively reduce the temperature inside the car. 4. After getting in the car, turn the external circulation to the maximum to expel the hot air inside the car. 5. When parking, you can park the car in a shady place, buy a car cover to shield the car, or leave some space in the window.

[Martinez]

Last week when picking up my kid from school, I parked my car in the open for just half an hour. When I measured the dashboard with an infrared thermometer, it was a shocking 65°C! I'm not exaggerating - in summer sunlight, car interiors can easily exceed 50°C within 30 minutes, with windshields getting hot enough to fry eggs. My child's water bottle left in the car warped from the heat. The scariest part? When it's only 30°C outside, cars with black interiors can reach over 70°C - I've seen plastic toys completely melted. Never, ever leave children or pets locked in a car, as heatstroke can occur within minutes. I've read news stories about parents having to smash windows to rescue forgotten children. Now I always park in shade when possible, and if there's none available, I use aluminum foil sunshades on the windshield - they really help lower temperatures.

[EmilyAnn]

The temperature in our office underground garage is 28°C, but after driving out into the open for just five minutes, even with the air conditioning set to maximum, it can't suppress the heatwave. Last Friday, the dashboard showed 43°C, and the moment my arm touched the leather seat, it almost scalded a blister. Experimental data suggests that dark-colored cars are about 10°C hotter inside than light-colored ones, with all-black interiors being even more extreme. A colleague's car without window tinting had a metal emblem on the steering wheel so hot it was unbearable to hold. My physics teacher once said that car glass acts like a greenhouse, allowing short-wave solar radiation in but trapping the long-wave radiation inside. It's recommended to remotely start the car's air conditioning 20 minutes before departure; otherwise, turning it on directly not only wastes fuel but also damages the compressor.

[ElainaMarie]

Just measured a customer's white SUV at the repair shop using an infrared thermometer. At noon with an outside temperature of 34°C, the dashboard reached 71°C, and the steering wheel was 68°C. The leather seat surface temperature could reach 63°C, and a water bottle left inside for a day was deformed. The principle is simple: the metal car body conducts heat quickly, the glass has over 80% light transmittance, and the air inside forms a closed-loop thermal convection. The most effective cooling method isn't blasting the AC, but first opening the doors for ventilation for two minutes before turning on the AC's external circulation. Tests show that using a silver sunshade can lower the dashboard temperature by 15°C, and installing magnetic side window shades is also practical—much easier to remove than regular curtains.

[VonMax]

Last year during the dog days of summer, I suffered heatstroke in my car and felt dizzy at the time. The doctor showed me a temperature chart and said: When it's 35°C outside, a turned-off vehicle heats up by 22°C in half an hour and can exceed 48°C in an hour. Even more dangerous is that in an enclosed space with humidity over 65%, the human body's sweat-based cooling mechanism fails. I later learned a life-saving tip: If you find someone trapped in a hot car, first check for chest movement. Don't rashly smash windows to avoid flying glass injuries. You can use a fire extinguisher to break a corner or use the metal part of a seatbelt as a window breaker. Now when parking, I always place my sun hat upside down on the steering wheel to somewhat protect the plastic parts.

[JamesonFitz]

Studying automotive thermodynamics reveals that the specific heat capacity of a metal car body is only 1/10 that of water, meaning it absorbs heat extremely quickly. Parking on concrete absorbs 40% more radiant heat than parking on grass, so it's recommended to park with the rear facing the sun to reduce sunlight exposure. I've tried several cooling methods: using an aluminum foil sunshade on the windshield can lower the temperature by 30 degrees; leaving the sunroof open more than 3 cm creates a convection effect; the most cost-effective method is lowering each window by 1 cm combined with tilting the sunroof. Recently, I've found that cars with remote start are particularly practical—using a mobile app to open the windows for ventilation before starting the AC can bring the temperature down to below 40 degrees by the time you get in, twice as fast as physical cooling methods and without draining the battery.