Why Even a “Mild” Day Can Be Deadly: What Every Parent Needs to Know About Car Heat and Babies

Why Even a “Mild” Day Can Be Deadly: What Every Parent Needs to Know About Car Heat and Babies

 - By Monica Bykov, RN, IBCLC, NCS - 

Never leave a baby in the car, not even for a minute.
It doesn’t have to be a scorching summer afternoon. In fact, even a cool 70°F day can turn a car into an oven within minutes, and for a baby, the danger escalates fast.

A Surprising Reality: Cars Heat Up Fast

We tend to think of temperature in terms of what feels comfortable to us as adults. But babies aren’t built like we are. Their bodies heat up three to five times faster than ours. They’re also unable to regulate their temperature well, and they don’t sweat efficiently.

You might be shocked to learn that according to a study published in Pediatrics, a car parked in the shade can still rise by more than 40°F within an hour—and 80% of that heat increase happens in the first 30 minutes (McLaren et al., 2005).

Let me put that into perspective:
If it’s just 72°F outside, your car could hit 110°F in under 30 minutes. That’s well into the danger zone for heatstroke.

What Happens to a Baby in a Hot Car?

When a baby is trapped in a rapidly heating car, their core body temperature can climb to lethal levels—even if the windows are cracked. Once a child’s internal temperature reaches 104°F, heatstroke becomes a serious threat. If it rises to 107°F, cells begin to die, organs shut down, and it can lead to permanent brain damage or death.

It happens more often than people think. According to the National Highway Traffic Safety Administration (NHTSA), an average of 38 children die each year from heatstroke after being left in a car—many of them babies.

And yes, some of those deaths happen when the weather is cool or cloudy. It’s not just summer that puts babies at risk.

But I’m Just Running In for a Minute…

As caregivers, we’ve all been there. The quick errand. The sleeping baby. The temptation to “just dash in.” But heatstroke doesn’t wait. And the risk is never worth it.

Also—let’s be real—how often does “a quick minute” turn into five? Or ten? Even two minutes is too long in the wrong conditions.

The Takeaway: Always Take the Baby With You

There is no safe amount of time to leave a baby in a parked car. Not in the shade. Not with the windows cracked. Not with the engine running. Not on a “cool” day.

Use visual cues to help yourself remember:

  • Put your diaper bag or phone in the backseat.

  • Place a stuffed animal in the front seat when your baby is in the back.

  • Set an alarm or reminder.

It’s not about being forgetful—it’s about being human. 

Final Thoughts from a Baby Nurse

The reality is, this is 100% preventable.
Always check the back seat. And always take the baby with you.

References:

  • McLaren, C., Null, J., & Quinn, J. (2005). Heat stress from enclosed vehicles: Moderate ambient temperatures cause significant temperature rise in enclosed vehicles. Pediatrics, 116(1), e109-e112.

  • National Highway Traffic Safety Administration (NHTSA). (2023). Child Heatstroke Deaths in Vehicles. https://www.nhtsa.gov