can a gun go off in a hot car

[VanJune]

The short answer is that it is extremely unlikely for a properly stored, modern firearm to discharge spontaneously in a hot car. The primary risk isn't the gun firing on its own, but rather the potential for negligent handling when you retrieve it or the damage extreme heat can cause to ammunition and the firearm itself.

For a cartridge to "cook off" or fire without a trigger pull, the temperature must be high enough to ignite the gunpowder primer. Most modern smokeless powders require sustained temperatures far beyond what a car interior can reach. A car's interior might hit 150-170°F (65-75°C) on a scorching day, but ammunition typically requires temperatures exceeding 300°F (150°C) to combust spontaneously. This is a critical safety margin.

However, the heat can still cause problems. Prolonged exposure to high temperatures can degrade the ammunition's propellant over time, potentially leading to inconsistent performance, misfires, or changes in pressure. The heat can also damage the firearm's lubricants, optics, and plastic components.

The real danger lies in improper storage. A gun left in a hot car is a security risk. Furthermore, if you leave a round in the chamber and the firearm is subjected to a significant mechanical shock, the risk of a negligent discharge exists, but that is unrelated to the heat. The safest practice is to store an unloaded firearm in a secure, locked container, out of direct sunlight, if it must be left in a vehicle.

Ammunition Type	Typical Cook-off Temperature Threshold	Notes
Modern Smokeless Powder	300°F - 400°F (150°C - 200°C)	Far exceeds typical car interior temperatures.
Black Powder	Lower than smokeless powder	Used in antique firearms; higher risk, but still unlikely in a car.
Nitrocellulose Propellant	Stable up to ~350°F (177°C)	Common in modern centerfire cartridges.

[AidenLee]

As someone who carries regularly, I don't worry about my gun going off from the heat. I worry about it getting stolen. The science is clear—it takes way more heat than a car can produce. My bigger concern is what the heat does to my gear over time. It can mess with the lubricants and even the ammunition if it's baking in there for weeks on end. My rule is to never leave it in the car longer than absolutely necessary, and it always stays in a locked safe bolted to the frame when it has to be there.

[GabrielaLee]

We live in Arizona, and our car becomes an oven. I was nervous about my husband's handgun until we asked a firearms instructor. He explained that it's practically impossible for the heat alone to cause a discharge. What stuck with me was his emphasis on handling. The gun is safe in the heat, but the danger is when you're hot, flustered, and reaching for it. That's when accidents happen. So now, our rule is about calm, deliberate handling, especially after the gun has been sitting in a hot car.

[McAmir]

From an engineering standpoint, the failure modes are important. The temperatures involved simply don't provide enough energy to initiate the controlled chemical reaction required to fire a round. Modern ammunition is designed with stabilizers for a wide range of environmental conditions. The mechanical safety mechanisms of a modern firearm are also not temperature-sensitive in that range. The probability of a thermal-induced discharge is statistically negligible compared to other risks like improper storage or handling negligence.

[StKeegan]

Look, I've been around guns my whole life, from the service to the range. I've left a shotgun in the truck bed in July and a pistol in the glovebox. They don't just go off. It's a myth that needs to be put to rest so people focus on the real issues: training and secure storage. If you're responsible enough to own a firearm, be responsible about where you stow it. A $20 console lock isn't enough. Use a proper safe. The heat won't set it off, but a thief in 30 seconds will.