SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/hot-car-cracked-window

Does cracking the windows keep a parked car cool on a warm day?

No. A car can heat up 20°F in 10 minutes, windows cracked or not.

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The Just Right card

Too littleCrack the windows and run in
Too muchLeave the engine and AC running
Just rightTake kids and pets with you

Huh, didn't know that: Inside a parked car it can get 40 to 50°F hotter than outside.

The dad joke
Why did the man put his car in the oven? He wanted a hot rod.
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References

Answer: No, it can heat 20°F in 10 minutes. A parked car can heat up 20°F in about 10 minutes, and cracking a window barely helps. Never leave kids or pets inside, even for a quick stop.

  1. CDC: Heat and Pets www.cdc.gov/heat-health/risk-factors/heat-and-pets.html
    Leaving a window open is not enough- temperatures inside the car can rise almost 20 degrees Fahrenheit within the first 10 minutes
    Checked 2026-10-09.
  2. South Carolina State Fire Marshal: Vehicular Heatstroke Prevention www.firesafe.sc.gov/weekly/Vehicular-Heat-Safety.pdf
    Interior vehicle temperatures can be between 40-50°F hotter than the outside.
    Checked 2026-10-09.

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