It’s 92°F outside. Your AC is humming. You’re cool. You’re focused. You’re a great driver.
So why did you almost hit that cyclist?
Because they weren’t.
Heat doesn’t care if you’re comfortable. It’s rewiring the people around you—and you’re the one paying for it.
Last year, 4 billion people—nearly half the planet—lived through at least 30 days of extreme heat. That’s not a headline. That’s your commute. That’s your kid’s soccer game. That’s the guy behind you who just cut you off without a blink.
And it’s not just "hot." It’s the kind of heat that turns a normal Tuesday into a statistical disaster. Climate change added 41 extra days of dangerous heat in 2024 alone. That’s not a trend. That’s a baseline shift. And every one of those days, the world got a little more dangerous behind the wheel.
I’ve seen it. I’ve felt it. I’ve almost been the victim of it.
I was in Phoenix last July. The air felt like a hair dryer held to your face. I was driving to a meeting. I saw a man on a bike, helmetless, swerving in the lane. I braked. He didn’t. He clipped my mirror.
He didn’t even look at me.
He just kept going.
I didn’t blame him.
I blamed the heat.
Because here’s the thing: heat doesn’t just make you uncomfortable. It makes you worse. It slows your reactions. It shrinks your attention span. It turns patience into rage and caution into carelessness. And it doesn’t matter how well you hydrate, how cool your cabin is, or how many times you’ve heard "drive safely." Your brain is compromised. And so are theirs.
This isn’t anecdotal. It’s quantified.
A 2017 study of 46 million U.S. crashes found that on days over 80°F, traffic fatalities jumped 8.6% compared to mild days. That’s not noise. That’s 1,200 extra deaths every summer. Just from heat.
And it’s not just drivers.
In Spain, researchers found that during heat waves, overall crash risk rose 2.9%. But when you isolate crashes caused by driver error—by bad decisions, by distraction, by impatience—the number jumped to 7.7%. That’s nearly triple the increase. Heat isn’t making roads slick or tires blow. It’s making drivers stupid.
Every 1°C rise in temperature? A 1.1% increase in driver-error crashes. In South Korea? 0.6%. In Italy? Even worse on the hottest days.
And here’s the kicker: those "hottest days" in Italy in 2015? They’d be considered mild now.
We’re not talking about an unusual summer. We’re talking about the new normal.
And the worst part?
You think you’re fine.
You’ve got your sunglasses on. Your seat’s cooled. You’re sipping water. You’re the responsible one.
But the guy in the minivan ahead of you? He’s got a screaming toddler. His AC is on its last breath. He’s been driving since 5 a.m. His brain is 1.5°C hotter than yours. He’s not thinking about lane changes. He’s thinking about getting home. And he’s not seeing you.
That’s not his fault.
It’s the heat’s.
And you’re next.
Because heat doesn’t discriminate.
You’re a worse driver when it’s hot.
I don’t care if you’re a veteran. I don’t care if you’ve never had a ticket. Your brain is slower. Your reflexes are duller. Your patience is thinner.
And so is everyone else’s.
I used to think road rage was a personality flaw.
Now I know: it’s a physiological response.
When your core temperature rises, your prefrontal cortex—the part of your brain that says "don’t do that"—starts to shut down. Your amygdala—the alarm bell that screams "threat!"—takes over.
So you tailgate.
You honk.
You flip someone off.
You don’t see the child running into the street.
You don’t see the cyclist.
You just see the guy who’s in your way.
And you forget that he’s just as baked as you are.
This isn’t about willpower.
It’s about biology.
And biology is losing this fight.
We’ve spent decades improving seatbelts, airbags, lane assist, automatic braking.
We’ve built cars that can park themselves.
But we’ve ignored the most dangerous component: the human in the driver’s seat.
And now, with heat pushing human cognition into a permanent state of impairment, we’re paying the price.
We’re not just seeing more crashes.
We’re seeing more avoidable crashes.
The kind that happen because someone didn’t check their blind spot.
Because they didn’t slow down.
Because they assumed the person in front of them had seen them.
Because they were too hot to care.
And here’s the brutal truth:
You can’t outsmart this.
You can’t hydrate your way out of it.
You can’t turn the AC up high enough.
The only thing that works is this:
Assume everyone around you is impaired.
Assume they can’t see you.
Assume they’re not going to brake.
Assume they’re going to cut you off.
And then, give them space.
Increase your following distance.
Reduce your speed by 20%.
Wear your helmet—even if it’s 95°F.
Don’t assume they’ll do the right thing.
Because they won’t.
And if you’re lucky, you’ll survive.
Because right now, the world is cooking our brains.
And the road is the most dangerous place to be when that happens.
The Numbers Don’t Lie—But They’re Not the Whole Story
Let me show you the data.
In 2024, the planet was 1.54°C hotter than pre-industrial levels. That’s not a rounding error. That’s a global fever.
And it’s not just the average. It’s the extremes.
Climate Central’s analysis found that in 195 countries, climate change at least doubled the number of extreme heat days. In some places, it quadrupled them. In others, it turned what used to be a once-in-a-decade event into a monthly occurrence.
And every one of those days? It’s another day the world is less safe on the road.
The numbers are terrifying:
- Traffic fatalities are 8.6% higher on days above 80°F. That’s 1,200 extra deaths every summer in the U.S. alone.
- In Spain, each 1°C rise in temperature means a 1.1% increase in driver-error crashes.
- In South Korea, the increase is 0.6% per 1°C.
- In Italy, the risk spikes on the hottest 25% of days—days that are now happening more than half the year.
And then there’s the exposure factor.
On hot days, more people are out. More cyclists. More pedestrians. More kids walking to school. More e-scooter riders zipping through intersections.
And they’re all more vulnerable.
They’re not in a steel cage with airbags. They’re exposed. Fragile. And when a driver’s judgment fails? They’re the ones who pay the price.
A 2021 study in Italy found that pedestrian deaths during heat waves increased disproportionately. Not because they were reckless. But because drivers weren’t paying attention.
I remember reading that study and thinking: that’s my neighbor. That’s my daughter’s friend. That’s the guy who delivers my groceries.
And then I realized: it’s not about them.
It’s about us.
Because the data doesn’t just show what’s happening.
It shows what we’re choosing to ignore.
We’ve built a world that assumes human behavior is constant.
That people are rational.
That they’ll slow down when it’s dangerous.
That they’ll wear a helmet.
That they’ll check their mirrors.
But we’re not constant.
We’re biological.
And when the thermometer rises, so does our irrationality.
We’ve spent billions on autonomous braking systems.
But we’ve spent nothing on understanding why drivers stop braking.
Why they stop seeing.
Why they stop caring.
Because we don’t want to admit it.
We don’t want to say: "It’s not the car. It’s the brain."
We don’t want to say: "It’s not the road. It’s the heat."
We want to blame the driver.
We want to blame the weather.
We want to blame the cyclist.
But the truth?
It’s the heat.
And it’s getting worse.
Every year.
Every day.
And it’s not going to stop.
Not unless we stop pretending we’re in control.
We’re not.
We’re just trying to survive it.
And the only way to survive is to act like you’re already compromised.
Because you are.
And so is everyone else.
What You Can Do—Before It’s Too Late
I’m not going to tell you to buy a better car.
I’m not going to tell you to install a dashcam.
I’m not even going to tell you to turn up the AC.
Because none of that fixes the problem.
The problem is your brain.
And everyone else’s.
So here’s what you do.
First: assume everyone is impaired.
I don’t care if they’re in a Tesla with adaptive cruise. I don’t care if they’re on a bike with lights. I don’t care if they’re a grandmother with a cane.
They’re hotter than you think.
They’re slower.
They’re distracted.
They’re not seeing you.
So give them space.
Increase your following distance. Not just a little. Double it. If you normally leave two car lengths, leave four. If you’re used to tailgating at 65, drop to 50.
And when you’re on a bike or scooter? Wear the helmet. Even if it’s 95°F. Even if it’s sweaty. Even if you think you’re "just going to the store."
Because the temptation to skip it? That’s the heat talking.
And it’s lying.
The helmet isn’t just for crashes.
It’s for the moment your brain decides to swerve.
The moment you don’t see the car pulling out.
The moment you lose balance.
You think you’re fine?
You’re not.
And neither is the driver who almost hit you.
Second: shift your schedule.
If you can, avoid driving between 1 p.m. and 6 p.m. on hot days.
That’s the peak window.
That’s when the brain is most impaired.
Work from home. Shift your hours. Take a nap. Walk instead of drive.
I know. You think you’re productive.
You think you’re being responsible.
But you’re not.
You’re just being stubborn.
And stubbornness kills.
Third: talk about it.
Don’t just say "be safe."
Say: "It’s hot. I’m slow. You’re slow. Let’s both take it easy."
Tell your kids.
Tell your coworkers.
Tell your partner.
Say: "I’m not myself when it’s hot. Neither are you. So let’s not pretend we are."
Because that’s the only way this changes.
Not with technology.
Not with laws.
Not with better roads.
But with awareness.
With humility.
With the willingness to admit: I’m not fine.
And neither are they.
And if we can’t do that?
Then we’re not just driving.
We’re waiting for the next crash.
And when it comes?
We’ll say: "I didn’t see it coming."
But we did.
We just chose not to believe it.
Because we didn’t want to admit the truth.
That we’re not in control.
That the planet is changing.
And that our brains are the first thing to break.
So do this.
Next time you’re driving on a hot day.
Pause.
Look around.
And ask yourself:
Are you really the safe one?
Or are you just the last one who hasn’t crashed yet?