How Hot Can it Get in a Closed Vehicle?

Don’t leave children or pets in a car while you run an errand – even if it’s just going to be for a few minutes. Temperatures can reach dangerous levels in a matter of minutes. An unscientific experiment was conducted at the National Weather Service Forecast Office near Sullivan, Wisconsin last summer. The object was to determine how quickly an automobile would heat up to levels that would pose a health hazard to children and pets left in a vehicle with the air-conditioner turned off.

It was a sunny day. The automobile was parked with the sun to the rear. The automobile was dark blue, so
it probably absorbed heat quicker and more efficiently than a light colored vehicle.

The simplified experiment consisted of putting an electronic thermometer inside a closed automobile, and one outside of the vehicle to measure ambient temperature in the shade. The interior and exterior readings were compared at timed increments.

The interior of the car was cooled to 83 degrees by the vehicle air conditioner, the engine was turned off and the monitoring was started. After only fifteen minutes the automobile interior heated to a deadly 120 degrees.

Here are the results;

Time          Interior temperature     Outside temperature
CDT               degrees F                      degrees F

1245 pm               83                                 92
100 pm               120                                 93
115 pm               123                                 94
130 pm               125                                 93
145 pm               127                                 94
200 pm               129                                 94
215 pm               130                                 95
230 pm               131                                 95
245 pm               132                                 95
300 pm               133                                 95
315 pm               134                                 95
330 pm               134                                 95

When hot temperatures occur it is important to not leave children or pets in parked vehicles, even for short periods of time.

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