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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 melt.

But how hot does your car get in these circumstances? Why does a car interior feel hotter than pretty much any other place on earth?

Read on as we answer the burning questions, including:

  • How do cars overheat?
  • What average temperature can car interiors reach?
  • Influencing factors that can increase the temperature

How do cars get so hot in the sun?

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 dashboard turning it into heat. Heat does not easily pass back through glass, so it’s 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 and only a few windows at a time are facing the sun.

As a result, they are easier to keep cool down — a typical car A/C is about as powerful as the units used to keep a small house or apartment cool.

How hot can your car get?

Studies show that the temperature of your car can increase between 10 and 20 degrees within just 10 minutes. This varies depending on the type of car, where it is parked, and the time of day.

The fastest temperature rise occurs in the first few minutes, getting even hotter over time:

  • 30 minutes – Interior temperature increases by an average of one degree per minute
  • 60 minutes – The average car is 43 degrees hotter than the outside temperature
  • 90 minutes – The average temperature difference is 48 degrees

If you leave your car for 30 minutes on a 90-degree day, you’ll return to a vehicle over 120 degrees inside.

After 90 minutes, this 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 to be around 160 degrees.

Since these are averages, there’s about a 50-50 chance that your car could get even hotter. The interior heat of your car can be influenced by many factors:

  • Exterior paint color
  • Interior upholstery color
  • Window tinting
  • Available shade
  • Direction parked
  • City where you are located

You can even find recipes for car-baked cookies – some cars really can feel just 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.

Use A/C Pro® to recharge your car’s A/C system quickly and easily, cooling you down in no time.

Make your air conditioner run faster and colder than when it was new with our proprietary formula. It won’t help you bake any cookies, but at least it will help keep your goose from getting cooked.

Check out our guide on how to cool down your car as quickly as possible for more tips for summer heat.