How hot is too hot to leave a pet in the car? Many sources say when the outside temperature is 70 degrees Fahrenheit, it’s too hot. This is a good guideline. Want more details? We got ‘em.
Heat exhaustion and heat stroke can start in dogs when their internal temperature reaches 104 degrees. Keep in mind that normal temperature in dogs is around 101 degrees. The temperature inside cars can get hot fast. We’ve been studying a scientific review written by forensic scientists concerning temperature variations in parked cars. When the outside temperature was measured at 75 degrees, the temperature in the cabin of a car has been measured at 118 degrees. That’s too hot. At 81 degrees, the cabin of the car reaches 138 degrees.
Cracking the windows has an effect, but not enough of one when the temperature is in the 70s. A one inch crack in all windows lowers the maximum cabin temperature by 5 degrees. A 2” crack in all windows lowers the cabin temperature by 10 degrees.
The outside temperature is not what really determines the temperature in the cabin of a closed car. It’s the radiant solar energy. One of the tricky things about cars heating up is that when radiant solar energy is on the rise, around the middle of the day, a car will heat up immediately. It takes two hours for outside air temperatures to respond to solar radiative changes. In other words, the temperature in a car will spike dramatically two hours before people can start feeling changes in the air temperature outside the car.
Data source: Dadour I, Almanjahie I, Fowkes N, et al. Temperature variations in a parked vehicle. Forensic Science International. Nov 10, 2010. PII: S0379-0738(10)00466-4