A car's interior temperature can become dangerously hot in the summer, easily exceeding 120°F (49°C) within just 60 minutes, even on a relatively mild 80°F (27°C) day. According to studies from the National Highway Traffic Safety Administration (NHTSA), the greenhouse effect caused by sunlight entering through the windows is the primary culprit. This rapid heating poses significant risks to health and safety, making it crucial to never leave children, pets, or sensitive items like electronics inside a parked car.
The rate of temperature increase is most dramatic within the first 15 to 30 minutes. The dashboard, steering wheel, and seats absorb solar energy and can reach temperatures high enough to cause burns. The actual maximum temperature depends heavily on several factors, primarily the outside air temperature and the intensity of direct sunlight.
| Outside Air Temperature | Estimated Interior Car Temperature After 60 Minutes | Key Risks at This Temperature |
|---|
| 80°F (27°C) | 120°F (49°C) | Heat exhaustion begins; dangerous for pets/children. |
| 85°F (29°C) | 130°F (54°C) | Risk of heatstroke increases significantly. |
| 90°F (32°C) | 134°F (57°C) | Skin burns can occur on contact with surfaces. |
| 95°F (35°C) | 140°F (60°C) | Extreme danger of life-threatening heatstroke. |
| 100°F (38°C) | 145°F (63°C) | Electronics and plastic components can warp/melt. |
Cracking the windows open slightly has a minimal effect on reducing the peak temperature, lowering it by perhaps only 10 degrees. The most effective strategy is to park in the shade or use a sunshade for the windshield. However, even shaded cars will become uncomfortably hot. Modern cars with remote start can help by allowing you to activate the air conditioning before you enter. The key takeaway is to always be aware of these extreme conditions and plan accordingly to ensure safety.
