We’ve all experienced getting into a parked car on a sunny day. It feels like you’re climbing inside an industrial-size oven, and all you can think about is getting the A/C running to cool it down before you get baked.
But how hot is it, really? Why does a car interior feel hotter than pretty much any other place on earth? And what can you do to keep it cool?
Greenhouse on Wheels
For starters, you’re not imagining it. A parked car interior really is the hottest place most people will visit in their lives (at least visit fully-clothed, if saunas are your thing).
The reason a car without cold air conditioning is hotter than the air around it — and hotter than a house or office without A/C — is because it really is a greenhouse on wheels. Other than the roof and support pillars, the top half of a car’s passenger compartment is mostly made of glass. Glass allows sunlight to pass through freely. Once inside the car, much of the light is absorbed by the seats and dash turning it into heat. Heat does not easily pass back through glass, so it is trapped inside the car. A parked car will always end up hotter than the air around it—usually much hotter.
A house or office with windows will also experience this greenhouse effect, but they have a much larger interior space to heat up. They also generally have a smaller percentage of glass letting light through (unless you literally live in a glass house), and only a few windows at a time are facing the sun. As a result, they don’t heat up as much, and are easier to keep cool — a typical car A/C is about as powerful as the units used to keep a small house or apartment cool.
So how high can the temperature inside your car go?
The exact answer will vary, of course, depending on the type of car, where it is parked, the time of day, etc. But there have been several studies to find the average temperature increase, and the results are uncomfortable:
- The fastest temperature rise occurs in the first few minutes. Within just 10 minutes, the temperature can increase between 10 and 20 degrees.
- Over the first 30 minutes, the temperature increases by an average of over one degree per minute. If you park and go inside a store for 30 minutes on a 90-degree day, you’ll come back to a car that is over 120 degrees.
- After one hour, the average car is 43 degrees hotter than the outside temperature.
- After 90 minutes, the average temperature difference is 48 degrees. On a 90-degree day, that equates to 138 degrees—higher than the hottest outdoor temperature ever recorded on earth.
- Interestingly, these temperature increases are roughly the same no matter what the outdoor temperature is. Even on a beautiful 75-degree day, the temperature after 90 minutes will be over 120 degrees. If you’re in a desert heat wave and the outside temperature is 110, expect a car interior around 160 degrees.
Since these are averages, there’s about a 50-50 chance that your car could get even hotter. The paint color, interior upholstery color, amount of window tinting, amount of shade, direction you are parked, and city where you are located can all affect whether your car is below or above average. You can even find recipes for car-baked cookies: some cars really can feel like an oven.
Having a cold A/C to quickly overcome this heat is important, both for comfort and for safety. If your A/C is low on refrigerant and not cooling the air, then all it can do is recirculate the same hot air—sort of like a convection oven.
You don’t have to suffer in the heat if your A/C isn’t cooling the way it should be. With a can of A/C Pro, you can quickly and easily recharge your car A/C system and get it cold again. Our proprietary formula can actually get your air conditioner running colder than when it was new, and cool your hot car faster. It won’t help you bake any cookies, but at least it will help keep your goose from getting cooked.