As the planet warms, heat waves and high-temperature days are becoming more common. This is dangerous for your health. As we saw in a previous post, heat might also cloud your brain and result in poor decisions.
It might also get you killed or injured because of poor decisions by others.
In research reported by the World Bank Group, Behrer and Bolotnyy (2024) examined administrative criminal records from Texas alongside weather data and found that arrests increase by up to 15 percent on hot days. The effect was driven by increases in violent crime. That is, burglars do not choose hot days more often than cold ones for break-ins, and pickpockets do not go out more when it is hot. Rather, people more often resort to unplanned, impulsive violence when temperatures are high. As Behrer and Bolotnyy found, higher incomes and newer housing counteract these effects, likely because both factors are associated with access to air conditioning and better cooling strategies.
In another study, Blakeslee and coauthors (2021) used data from 600 police stations in India between 2011 and 2016, combined with daily weather records, to examine the relationship between crime and temperature. They found that violent, impulsive crimes, including violence against women and ethnically motivated violence, responded to both daily and seasonal temperature variation. There is more violent crime on hotter days, but also more violent crime when it is hotter at any given point during the day. Property crimes such as break-ins showed seasonal variation, but no relationship to within-day temperatures.
In the Heat of the Moment
Many other studies have reached similar conclusions. Heat increases non-property, impulsive crime more than property crime, and it has a much larger impact on violent crimes and crimes of passion.
This is not surprising. As discussed in the previous post, when temperatures are too high, your body attempts to cool you down, which, at the risk of oversimplifying a complex topic, may disrupt blood flow to the brain and result in poor judgment. When decision-making is impaired, intuition and impulses tend to take over.
If things do not go your way, it is perfectly normal to feel frustrated or even angry. Being a functioning member of society does not require suppressing all emotional reactions. It requires controlling them and not overreacting. When impulses take over, more people overreact and become physical after even minor slights, real, perceived, or imagined.
Going Outside
The simplest explanation for the correlation between high temperatures and violent crime is that heat impairs impulse control and thus increases spur-of-the-moment aggression. But the picture is more complicated.
Cohen and Gonzalez (2024) combined administrative records, surveys on unreported crime, and daily weather reports to study the relationship between temperature and crime in Mexico. They found that for every 1°C increase in temperature, criminal charges increase by 1.78 percent, even at comfortable temperatures. As in many other studies, the effects are stronger for violent crimes, including homicides, sexual crimes, and family violence.
Cohen and Gonzalez also found that part of the increase in violent crime on hot days is related to changes in how people spend their time. When it is hot, people spend more time outside their homes. Since the large majority of violent crimes occur outside the victim’s home, part of the increase is simply a matter of exposure and opportunity. For example, the temperature’s effect on crime is much stronger on weekends than on weekdays, when people have more freedom as to where they spend their time.
There is one more factor. When it is hot, people drink more fluids, as they should. But they also drink more alcohol, which lowers impulse control further. In Cohen and Gonzalez’s data, around 29 percent of all weather-induced crimes were committed by drunk offenders.
Beware of Hot Days
As discussed in the previous post, heat might cloud your judgment. It might also cloud the judgment of those around you. Even if you remain calm and controlled, on a hot day, you might be more likely to be drawn into a situation that would be better avoided.
First, be alert to other people’s tempers. Nobody is fully rational, and heat does not help. Give people space, defuse rather than escalate, and stay cool.
Second, think carefully about where you place yourself. A hot day may not be the best occasion to explore an unfamiliar neighbourhood or one where alcohol is flowing freely. When in doubt, stick to public places with visible security (and AC).
Third, check yourself. If you can have a short temper on occasion, make an extra effort on hot days. Cool down, drink water, stay in the shade. Your fellow human beings, and probably the people closest to you, will be grateful.