Did I Park Right How hot does a parked car get?
A parked car in the sun gets about 40°F hotter than outside within an hour, and 80% of that rise comes in the first 30 minutes, even on a cool day. That’s from a 2005 Pediatrics study. Cracking the windows made no real difference. Enter the temperature below to see the estimate.
McLaren, Null & Quinn, Pediatrics 2005 · NHTSA
How the estimate works
The study measured a dark sedan in full sun on 16 clear days from 72 to 96°F outside. The rise averaged about 41°F after an hour, with a range of 28 to 49°F, and 80% of it came in the first 30 minutes. Even at 72°F outside, the car reached 117°F. Our curve is a smooth line through those published numbers, so treat it as an estimate. A lighter car, shade or a different day will change it.
Inside the car, by minute
Estimate for a dark sedan in full sun, from the study’s average rise.
Children and pets
There is no safe time. NHTSA says never to leave a child in a vehicle unattended for any length of time, and that rolling windows down or parking in the shade does little to change the temperature inside. It says heatstroke begins at a core temperature of about 104 degrees, and about 107 is lethal. If you see a child alone in a car, call 911.
The same physics applies to pets.
The same physics applies to pets. There is no safe time.
Things you leave in the car
Phones, batteries, medicines and aerosol cans are the items to bring with you. Your phone’s maker sets an operating range, and a hot car can pass it quickly. Check the label or the leaflet for anything that says to store below a set temperature.
Parking in a garage? It helps with the sun, but note your garage level before you walk away.
Estimated temperature inside the car
| Outside | 10 min | 20 min | 30 min | 60 min |
|---|---|---|---|---|
| 75°F | 93°F | 103°F | 108°F | 116°F |
| 85°F | 103°F | 113°F | 118°F | 126°F |
| 95°F | 113°F | 123°F | 128°F | 136°F |
Estimates for a dark sedan in full sun, from the study’s average rise. Temperature only. No time is safe for a child or a pet.
Inside the car after 30 minutes in full sun, estimate.
What to do next
Quick answers
How hot does a car get at 85 degrees outside?
About 118°F after 30 minutes and 126°F after an hour in full sun, by our estimate from the Pediatrics study.
Does cracking the windows help?
Not much. The study found it made no real difference to the rate of heating or the maximum temperature.
How long can a dog stay in a car?
Don’t leave one. A car can heat up fast even on a mild day, and there is no safe time.
Sources: McLaren, Null & Quinn, Pediatrics 2005 · NHTSA — Heatstroke
Reviewed : study figures re-read from the paper. NHTSA guidance re-read · how we check · report an error