National Weather Service Weather Forecast Office

Ever wonder how hot it can get inside a closed vehicle...one that has all the windows closed?  We conducted an experiment back in July, 2006, to find out just how hot it can get.  The results,  shown below in a Public Information Statement we issued on July 31, 2006, suggest that temperatures inside a closed vehicle on a sunny day can be on the order of 35 to 40 degrees warmer than the air temperature outside the vehicle!  Don’t take any chances during sunny weather - don’t leave children or pets inside closed vehicles!

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
332 PM CDT MON JUL 31 2006

...DEADLY TEMPERATURES CAN BE REACHED QUICKLY IN VEHICLES...

AN UNSCIENTIFIC EXPERIMENT WAS CONDUCTED AT THE NATIONAL WEATHER
SERVICE FORECAST OFFICE NEAR SULLIVAN TODAY...MONDAY JULY 31 2006.
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 TODAY. THE AUTOMOBILE WAS PARKED WITH THE SUN TO THE
REAR...AND THE FRONT DRIVER AND PASSENGER COMPARTMENT WAS SHADED
FROM THE DIRECT RAYS OF THE SUN. 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. WE THEN
COMPARED THE INTERIOR AND EXTERIOR READS AGAINST EACH OTHER AT TIMED
INCREMENTS.

WITH THE AUTOMOBILE COOLED TO 83 DEGREES FAHRENHEIT BY THE VEHICLE
AIR CONDITIONER...THE ENGINE WAS TURNED OFF AND THE MONITORING WAS
STARTED AT 1245 PM CDT. AFTER ONLY TEN MINUTES...THE AUTOMOBILE
INTERIOR HEATED TO A DEADLY 119 DEGREES FAHRENHEIT...WHILE THE
OUTSIDE TEMPERATURE WAS A DANGEROUS 92 DEGREES FAHRENHEIT.

HERE ARE THE RESULTS OF WHAT WE OBSERVED OVER THE NEXT COUPLE HOURS...

TIME          INTERIOR TEMPERATURE          AMBIENT TEMPERATURE
CDT            DEGREES FAHRENHEIT           DEGREES FAHRENHEIT

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

THUS...WHEN HOT TEMPERATURES OCCUR...IT IS IMPORTANT TO NOT LEAVE
CHILDREN OR PETS IN PARKED VEHICLES...EVEN FOR SHORT PERIODS OF
TIME. AS THIS UNSCIENTIFIC STUDY SHOWED...TEMPERATURES CAN REACH
DEADLY LEVELS IN A MATTER OF MINUTES.