What Causes Violent Crime to Decrease in the Winter?
Kevin Wolff, a professor at the City University of New York’s John Jay College of Criminal Justice who researches the relationship between crime and weather patterns, tells A&E Crime + Investigation that the “seasonality of violent crime is pretty well known.” Wolff credits this to “routine activity theory,” wherein crime happens when “a motivated offender and a suitable target occur within a time and space in the absence of a capable guardian.”
“The cool thing about weather and crime is that it makes sense to people on some level,” Wolff adds. “We plan on being in front of our fireplace on Sunday reading books, and so our victimization risk is pretty minimal.”
That said, there are competing factors that—under different circumstances—should drive crime upward in the winter. Most notably, there are longer nights.
Ernesto Lopez, a researcher at the Council on Criminal Justice, which does extensive work looking at monthly crime trends across large American cities, tells A&E Crime + Investigation in regards to daylight ”the more you light an area, the more you see a reduction in crime,” but that it isn’t enough to offset the comparative lull to the summer.
That’s because, Lopez says, there are more people out, including teenagers and young adults who might otherwise be in school.
“While youth don’t commit as many crimes as adults, it’s still an increase in their unsupervised time,” Lopez says.
Are There Exceptions to the Decrease?
Not every day in the winter sees a decrease in crime. Some major holidays cause people to go out more, which in turn drives crime upward. According to Lopez, New Year’s Eve “usually brings a bunch of assaults,” although not enough to meaningfully drive the trendline of the month. Wolff’s research supports that point.
“Major U.S. holidays are positive [in correlation] for assault and homicide, but negative for robbery, which makes sense, because robbery is different from assault and homicide. On holidays you’re around people, but you usually know those people,” he says, adding that robbery is usually perpetrated against strangers.
Much of Wolff’s research has been about the impact of unseasonably warm or cold days on crime trends. When looking at violent crime in 28 cities throughout the United States, Wolff found that an exceptionally warm winter day drives up assault, robbery and homicide, even more than if that same moderate temperature were to occur at a seasonally appropriate time. When the weather is unseasonably cold, the opposite occurs. This suggests that it isn’t just the temperature itself, but the “departure from the norm” that cues human behavior.
According to Lopez, there’s also stronger variance in the cities with stronger seasonal differentiation. So whereas Chicago and Detroit experience wide variation between summer and winter, Los Angeles and Austin see flatter crime rates.
Given that people spend more time at home in the winter, it would be reasonable to imagine that domestic violence cases would go up. However, Lopez says that, like the rest of violent crime, domestic violence goes down during the winter and up in the summer. He doesn’t know why but says that the increased time at home with potential perpetrators might be offset by the reduced number of interactions, more broadly, with the world at large.
“There’s never one explanation for crime,” he says. “There are competing elements pulling potential crime rates.”
Any Other Explanations?
In addition to the increased amount of time spent outside, there’s also a theory that suggests that aggression levels rise when the weather gets warmer and then drop when it’s colder. There’s some data that supports this theory. During heat waves, violence increases not only interpersonally but also against the self, with rates of suicide spiking in the hottest days of the year.
The winter, meanwhile, tends to be correlated with lessened travel, especially to places with harsh winters—which, in turn, drives down crime rates, Lopez says.
Lopez adds that the relationship between temperature and crime isn’t purely linear; in some places, too much heat can decrease crime if it gets too hot for people to spend time outdoors, such as the Southwest in August. This bell curve of crime suggests that humans have a "Goldilocks zone" for everything—including mayhem.
