"On a 90-degree day, the inside of a car parked directly in the sunlight can climb above 130 degrees," said Kandace Redd with the Automobile Club of Southern California.
But there are ways to keep your car a bit cooler so it's not so much like an oven when you first step into it.
For example, this may sound obvious but find shade if you can. More parking lots have added shady space with overhead solar arrays.
Popping up in places like shopping centers and school parking lots, these keep cars cooler while capturing the sun's energy for electricity.
Can't find shade? You can bring your own, in a way.
Those folding windshield shades may seem gimmicky, but they really work to keep the inside a bit cooler!
On most vehicles, the windshield is the largest piece of glass and lets in a lot of solar heat.
A parked car can have its inside temps soaring, even if you're only stopping for a quick lunch or doing some shopping.
Heat builds up very rapidly, and those kinds of temperature extremes can lead to the tragedy of children being accidentally left inside.
"We know that more than 1,000 children have died from heat stroke in hot cars. This is over the past 25 years," noted Redd.
Plus, technology helps.
Most new and late-model cars have reminder systems to check the rear seat before you leave.
Nissan's Rear Seat Alert - developed by two working mothers at the company - goes one step further by beeping the horn after you close the driver's door.
An extra reminder that there may be something in the rear seat. Not just for kids and pets, but leaving a bag of groceries in an oven-hot interior could be a pricey mistake, too.
Nissan now includes Rear Seat Alert on all its cars, SUVs and pickups with four doors.
And a growing trend to help cool down that roasting interior before you even get in: remote start.
First pioneered by General Motors many years ago, many auto brands now offer it, even in their lower-priced cars. It's usually activated by a button on the remote fob, or sometimes by an app linked to your vehicle.
You can start the engine (or electric system on an EV) and let the air conditioning start doing its job.
This can be done from inside your home, or a business where your vehicle is parked nearby. The car remains locked until you reach it, and you'll find a much cooler interior.
It also works in the winter to warm the car when the weather is cold.