how hot can the trunk of a car get

[LeLucy]

A car trunk can become dangerously hot, reaching internal temperatures of 130°F to 195°F (54°C to 90°C) on a sunny day. This extreme heat is a significant safety hazard and can damage belongings. The temperature depends heavily on the outside air temperature, the color of the car, and how long it's parked in direct sunlight.

The primary reason for this heat buildup is the greenhouse effect. Sunlight passes through the car's windows, and the interior surfaces, including the trunk walls, absorb the energy and re-radiate it as heat. Since the trunk is an enclosed, insulated space with little air circulation, the heat becomes trapped and intensifies.

It's crucial to understand that high heat can damage or destroy common items. For example, electronics can malfunction, medications can lose potency, and aerosol cans can explode. A study by the San Jose State University Department of Meteorology and Climate Science recorded the following temperatures inside vehicles:

Outside Air Temperature	Elapsed Time	Interior Cabin Temperature	Trunk Temperature (Estimated)
80°F (27°C)	30 minutes	109°F (43°C)	115-125°F (46-52°C)
90°F (32°C)	60 minutes	124°F (51°C)	135-145°F (57-63°C)
95°F (35°C)	60 minutes	130°F (54°C)	150-160°F (66-71°C)
100°F (38°C)	60 minutes	140°F (60°C)	170-180°F (77-82°C)

To protect your items, never leave anything heat-sensitive in the trunk for extended periods. If you must store something, park in the shade, use a sunshade for the rear window, and consider a light-colored car which absorbs less heat than a dark-colored one. The safest rule is to treat your trunk like an oven—it's not a storage closet.

[LeCorey]

I learned this the hard way after leaving a case of water bottles in my trunk overnight during a summer road trip. The next morning, the plastic bottles had warped and the water was almost too hot to drink. It really hit home that the trunk offers zero protection from heat. Now, I never leave groceries, my kid's sports equipment, or anything plastic back there if I'm not going straight home. It’s just not worth the risk.

[DeEmily]

Think of your trunk as a poorly insulated metal box. On a hot day, the sun heats the exterior, and that heat soaks right through. Dark-colored cars get even hotter. The air inside gets trapped and has nowhere to go, so the temperature just keeps climbing. It’s basic physics. This is why you should never store emergency supplies like bottled water or important medications in your trunk long-term; the extreme heat will ruin them.

[Adriana]

As someone who commutes daily, I'm always throwing my work bag and gym duffel in the trunk. I never thought much about it until my phone charger cord I kept in the bag became brittle and cracked. The heat broke down the plastic. Now I'm careful about what I leave in there. Electronics, batteries, even canned soda—they're all vulnerable. That space gets much hotter than people realize, and it can quietly destroy your stuff.

[NolanLynn]

The main heat sources are solar radiation on the car's exterior and the greenhouse effect from the rear window. A trunk's temperature can be 30-40 degrees Fahrenheit hotter than the outside air. The most critical risks involve items like aerosol cans (which can explode), lithium-ion batteries (fire hazard), and of course, children or pets, which is a life-threatening situation. Always remove heat-sensitive items immediately and never use the trunk as permanent storage.