"Cars can become like a little oven," said Dr. Ellen Lauer, with PCHC Pediatrics.
52 kids died in hot cars last year according to Kids and Cars.
And while none of those kids were in Maine, pediatricians and emergency personnel are reminding the public to not leave children unattended.
Medical professionals said inside a car, the temperature can raise twenty degrees in just ten minutes, and that cracking a window doesn't help.
"If it's 90 degrees outside, ten minutes, it's 110 degrees in your car," said Dr. Lauer.
While it may seem like common sense, doctors said accidents happen, especially with a routine change like when someone is watching another person's kid.
They're also reminding the public to make sure kids know trunks of cars are not a place to play.
"It's recommended to sort of have something to remind you to look in the back seat so they say to leave your cell phone back there or your purse," said Dr. Lauer.
Doctors at PCHC in Bangor said they've seen milder heat stroke cases in kids left unattended.
More severe cases can lead to seizures and unconsciousness.
Since children aren't as developed, they don't sweat as much and can't regulate their body temperature like adults can.
The same goes for pets.
"I know the police department does a lot of animal problem checks...it keeps the animal control officer very busy," said Bangor Fire Department Assistant Fire Chief Chandler Corriveau.
Doctors said if you see a child in a hot car, look first for a guardian, and tap on the window to see if the child is responsive.
Those at the Bangor Fire Department agree that all these situations are preventable.
"The biggest thing is if you come across anything and you have any concern for a pet or a child or even an adult call 911," said Assistant Chief Corriveau.