Why Does the Heat Make People More Violent?

4 minute read

By Christopher Brown

Whether someone lost their cool or became a hot-head, it’s no secret that people associate heat with aggression and even violence. But, does heat really impact our behavior? Start a search today to explore the relationship between heat and violence.

Can seasonal heat waves really be the cause of periodic crime spikes? Let’s turn up the thermostat and scour the internet to bring you all of the latest on the relationship between your thermometer and your patience.

What Is Hot?

Before we get all hot and bothered, we should probably set the ground rules. Though comfort is relative, and dependent on a whole host of different factors, 72 degrees Fahrenheit, also known as room temperature, is widely recognized as “comfortable” for most people.

“Hot,” in turn, should be understood to mean any temperature about 78 Degrees Fahrenheit and higher. (That is, unless you’re my dog. Then, anything above freezing is much too warm.)

A History of Violence

Before we tackle the why, let’s take a look at some real-life examples of the heat’s effect on human behavior. In an article for the Atlantic, Olga Khazan breaks down a study that attempts to link periods of dramatic climate change with periods of violent instability. Based on the data she looked at, an increase in temperature is clearly linked to an increase in conflict.

Why? No one is exactly sure. But, forced migration and a lack of available resources probably played a significant factor historically.

Crime vs. Weather in Chicago

Heat’s association with violence and instability isn’t just a relic of ancient times. Associate Professor Ellen G. Cohn of Florida International University proved this when she plotted violent crime in Chicago against the precise temperature of the region at the time that the infraction was committed.

The result? Crime steadily rose with the temperature — that is, until the thermometer hit 89 Degrees Fahrenheit. At that point, crime took a significant nosedive.


So we’ve established a link between crime and heat. But the real question is why? Well, there’s a lot of discussion on that topic as well.

Have you ever been so uncomfortable and so irritated that keeping your cool takes everything you’ve got? Now, just imagine that, minus the air conditioning. The emergency room, the dentist’s office, the DMV… take people out of their comfort zone and they’ll naturally get a little testy! The heat makes people uncomfortable, and in turn, more irritable.


The heat does a number of different things to us humans on a biological level. It increases our heart rate, it affects the way that we metabolize food and can even increase the rate at which testosterone is produced in some people. It’s like a pseudo fight-or-flight biological scenario. It affects our decision making, causing us to act unconventionally.

Brain Drain

Violence begins where your ability to reason ends. And, more and more studies show that your capacity to think logically is dramatically impacted when the temperature of your brain is warmer than usual.

Cooler climates have been linked to an increase in critical thinking ability. And, based on anecdotal evidence, we know that warmer climates increase the likelihood of jumping into the lake with your phone in your pocket.  Not that I’ve ever done that, of course.


An increase in aggressive behaviour has also been linked to dehydration! University of Connecticut researchers discovered that even mild dehydration in test subjects can cause significant, mood altering effects. Headaches, fatigue, difficulty concentrating and an increase in tension could all be linked to a lack of necessary fluids.

Thinking about really laying into that telemarketer? Just hang up the phone and grab a delicious glass of H20.

Road Rage

If the sky is blue and the weather is warm, don’t be surprised if you see a few more cop cars and speed traps along your morning commute. Why? Because police officers know that the nicer the weather, the more dangerous the drivers.

Studies show that motorists drive more cautiously during inclement weather, and more aggressively when the roads are clear. Aggressive driving leads to road rage, which can often lead to violence.

Summer SAD

Does the sunshine make you grouchy, depressed or anxious? You could be experiencing Summer Seasonal Affect Disorder. Summer SAD affects up to 2% of the population, and often hits at the tail end of spring or the beginning of summer. Common symptoms include a lack of energy, moodiness and depression.


I can’t be the only person in the world that goes a little red when I open my summer utility bill. Electricity costs can put a big dent in your summer vacation plans in no time, and that’s enough to make even the calmest person’s blood boil.

Party Season

Though the link between violence and the weather forecast is still very, very loose, the link between substance abuse and violence is statistically proven. And, you know… summer is for partying, right?

According to the NCADD, alcohol is a factor in 40% of all violent crimes today. Feel free to let loose, but please… drink responsibly.

Chill Out

Ahhh, summer. What’s not to love? Sunburns, heat stroke and an uncontrollable urge to hit someone really, really hard. Well, not exactly.

Though we’ve established a few links between heat and violence, we’re still a long way away from actually proving absolute causation. Either way, I’m going to mix me a margarita, sit in the shade and listen to some soothing, ocean sounds. Cheers!

Christopher Brown