how hot can car get on a summer day

[Genevieve]

A car's interior temperature can become dangerously hot, far exceeding the outdoor air temperature. On a typical 85°F (29°C) summer day, the inside of a parked car can reach a scorching 120°F (49°C) within just 30 minutes. On extremely hot days above 95°F (35°C), interior temperatures can soar to 140-150°F (60-65°C) or even higher within an hour. This rapid heating effect, known as the greenhouse effect, turns a vehicle into an oven, posing severe risks to people and pets.

The rate of temperature increase is not linear; it is most dramatic in the first 15-30 minutes. The dashboard, steering wheel, and seats absorb solar radiation and become significantly hotter than the air, often reaching temperatures capable of causing burns. The color of the car's interior and exterior, along with window tinting, can influence the final temperature, but the risk remains high in direct sunlight.

The following table illustrates how quickly temperatures can rise on a sunny day with an outside temperature of approximately 90°F (32°C).

Time Elapsed	Approximate Interior Temperature
0 minutes	90°F (32°C)
10 minutes	105°F (41°C)
20 minutes	115°F (46°C)
30 minutes	125°F (52°C)
60 minutes	140°F (60°C)

It is critical to understand that cracking a window open has a minimal effect on slowing this heating process. Studies from institutions like Stanford University Medical Center have shown that the interior temperature still rises to dangerous levels. The most important takeaway is to never leave children, elderly individuals, or pets unattended in a parked car, even for a short period. Always check the back seat before locking the vehicle.

[EllieAnn]

It gets unbelievably hot, way faster than you'd think. I once left a chocolate bar on the seat, and it was a melted mess in under ten minutes. If it's 90 degrees outside, your car can feel like an oven in no time. I never, ever leave my dog in the car, not even with the windows down a bit. It's just not worth the risk. The steering wheel alone can burn your hands. Always find a shady spot, but even that only helps so much.

[JacksonRose]

The primary mechanism is the greenhouse effect. Solar radiation passes through the glass windows, and the interior surfaces—dashboard, seats, and steering wheel—absorb this energy. They then re-radiate the energy as heat, which is trapped inside the cabin. The temperature rise is exponential in the first half-hour. Variables include solar intensity, ambient humidity, and the vehicle's color. A dark interior can be 15-20 degrees Fahrenheit hotter than a light one under identical conditions. Proper window tinting that blocks infrared radiation is the most effective countermeasure.

[DiNathan]

My trick is to use a sunshade for the windshield every single time I park. It makes a huge difference when you get back in. I also try to park facing the sun so the back window, which is usually more vertical, takes the brunt of the heat instead of the large, sloped windshield. If I know it's going to be a scorcher, I'll leave the sunroof cracked open just a tiny bit to let some hot air escape. It doesn't stop it from getting hot, but it takes the edge off. Leather seats are the worst in summer; I always keep a towel in the car to drape over them.