III. Theoretical Models of the Relationship of Weather and Crime
A. Early Explanations
Early philosophers believed that the weather had an effect on the biological and psychological makeup of individuals, and thus of cultures, with temperate climates making for temperate personalities and hotter climates making for more aggressive personalities. Characteristically, they argued that hotter days, hot seasons, and hot climates influenced individuals directly, making them less capable of controlling their inhibitions and more subject to impulsive and often aggressive behavior. Society, then, merely reflected those individual influences.
During the birth of modern social science in the 1800s, a Belgian statistician named Adolphe Quetelet formulated the thermic law of delinquency, which held that crimes against person are more common in hotter climates and seasons, whereas crimes against property are more common in cooler climates and seasons. During the rest of that century and into the 20th century, many of the first criminologists, from Cesare Lombroso and Enrico Ferri to Gustav Aschaffenburg, supported this thermic law. In the United States, some researchers blamed excessive heat for stimulating the emotions, increasing irritability, and bringing about lower levels of social inhibition, with a resultant inability to control one’s impulses. All of these factors, they argued, led to the higher murder rates seen in the hotter southern areas of the United States. This was carried further to a racist climatic determinism that argued that blacks, tracing their ancestry to the hot regions of Africa, carried a hereditary tendency to aggression and lower impulse control derived from that climate, which resulted in the higher murder rates among African Americans.
Others, however, rejected this biological determinism and began to observe that the correlation of weather and crime was mediated by culture and the changing nature of social interactions (Falk, 1952, provided an excellent review of this literature). In his comprehensive examination of suicide as a social phenomenon, one of the outstanding early sociologists, Emile Durkheim (1897/1951), countered these explanations and the thermic law of delinquency. Examining data on crime as well as suicide, he was one of the first scholars to bring a systematic scientific method to bear on the relationship of weather to crime. He pointed out that the patterns of personal aggression, both murder and suicide, that appear characteristic of certain climates at one time in history are not necessarily characteristic of those same climates at other times in history. He also demonstrated that within any climate different subcultures in the population will display different levels of aggression. It is, he argued, not the climate but the culturally framed social activity of the people who live in that climate that fosters or prevents aggression.
In examining seasonality, Durkheim (1897/1951) used data on Europe from much of the 1800s that did in fact indicate higher murder rates and suicide rates in the summer. However, after an analysis of those data, he concluded that it is not heat per se that brings about changes in the individual that lead him or her to commit murder or suicide. He argued that instead, the rates for those instances of premature or voluntary death occur during the summer because during that season social life is far more active, and social interactions are more intense. In noting this he was among the first to understand that the influence of weather, including seasonal or climatic effects, was indirect, bringing about changes in social interactions, which then changed the levels of crime and suicide.
B. Modern Theories
During the growth of modern criminology in the 20th century, theorists increasingly came to follow Durkheim’s lead and examined how weather, climate, or season affects our day-to-day social interactions. Throughout the century, a variety of explanations were tested using increasingly sophisticated methods, and by the beginning of the 21st century two models had evolved to explain weather’s impact on crime: (1) interactional theories focusing on stress and (2) routine activities theory.
Interactional theories look at the relationship of the individual to the social milieu in which he or she lives. In short, how do people manage to get along with each other day to day? In this model, stress—the need to constantly adapt to changing conditions and accommodate others in social interaction—is a constant in all human behavior. We react and respond to our environment using socially learned habits of adaptation provided by our culture. That environment consists not only of other people and our interactions with other people but also the physical world. These adaptations usually are quite functional and allow the individual to deal with normal levels of stress. In cases of extreme weather, however, these normal adaptations are stretched beyond their functional limits, and normal physical, psychological, and social reactions begin to break down.
The way we are taught to accommodate increased stress brought about by hot weather, and even the way we are allowed to accommodate, is culturally, socially, and economically conditioned. In very hot weather in public work settings in the United States, men may take their shirts off. Women, by law and by cultural convention, may not. In very hot weather, middle- and higher-class people can stay inside their air-conditioned homes. The poor, unable to afford air conditioners and the energy to run them, cannot. In other words, the way groups of people are able to adapt to increased stress is based on everything from economic status to gender. During times of stress, these differences can result in increases in criminal behavior in some populations more so than others.
This stress is not all social or psychological. Heat has a very real physical impact on our bodies. During periods of increased heat we perspire, and blood flow is increased near the skin to better dissipate heat. However, at some point our bodies are physically unable to keep up with the stress produced by increasing heat (and accented by increasing humidity). Research has established that there are qualitative points, called discomfort points, at which heat (or the relationship of heat and humidity) begins to noticeably affect most people, and those points show up as having a relationship to some crimes, notably, assault and murder.
Beyond the biology of the individual, however, crimes are more often the result of stresses that derive from human interaction, and both weather and season change our patterns of behavior and thus, indirectly, the nature and level of stress to which we are subjected. These common patterns of behavior are called routine activities, and they are the focus of the second major approach to understanding the impact of weather and season on crime.
Routine activities theory, developed by Cohen and Felson (1979), is probably the most widely used model to explain the relationship of weather, climate, and season to crime. This theory holds that crime is the result of the convergence in time and in space of motivated offenders, suitable targets, and the absence of capable guardians. Note that it is not a causal theory that seeks to explain why individuals become motivated to commit crime; instead, it simply states that when people who might decide to commit a crime (or who are already intent on committing a crime) wind up at the same place and at the same time as people or places that are suitable targets, and there are no other people or structures or props present that can protect those suitable targets, crime will increase.
Weather, climate, and season can have an impact on all three of those components (i.e., motivated offenders, suitable targets, and lack of guardians). The time around Christmas, for example, often finds us economically stressed, with an immediate need for cash to buy presents (or to pay bills from credit cards used to buy those presents). Field studies of armed robbers have revealed that robbery is often the result of a perceived need for immediate cash and that the preferred targets are individuals who are likely to have cash or valuables and unlikely to have a defensive weapon. Those two factors predominate around Christmas. Furthermore, the mass of shoppers in malls and in parking lots can overwhelm security personnel and normal security measures, leaving the suitable targets without adequate guardianship. And sure enough, FBI data confirm that robbery is the only Crime Index crime that is regularly more common in the deep winter months (December and January; Falk, 1952).
Even a look at the same type of crime, but different sets of victims, reveals that the common activities in which people engage are significant influences on the crimes they commit. McCleary and Chew (2002) examined seasonal risks for homicide but focused on victims who were children under age 15. They confirmed that the summer season peak found for adult victims was also characteristic of school-aged children, but for children under age 5 they found a significant peak in homicide victimization during the winter months. Most offenders in these child murders were young mothers, and the event precipitating the homicide was likely to have involved demands for food, clothing, or attention. These demands were most likely made at home, were more stressful for young mothers with less experience, and were accented during winter months, all of which explain the higher murder rates for young children during that season.
In research that compared routine activities theory with a more traditional psychological theory suggesting a direct association of temperature and aggression, Hipp and colleagues (Hipp, Bauer, Curran, & Bollen, 2004) found that routine activities theory was more effective in explaining the differences found in both violent and property crime. As we will see, data on a variety of different crimes over a number of years and in a variety of places support that conclusion. It is also important to point out that we have to be very careful not to confuse levels of scale when comparing a sociological theory such as routine activities theory with a biological or psychological theory. Even when considering stress, we have to be careful to make sure our data and our theory are derived at the same level of scale. Durkheim (1897/1951) pointed out that one should explain social facts only with other social facts. If we have data on crime rates that are derived from large population groups, for example, we have to be sure our theories are not reducing our explanations for a group’s crime rate to the psychological makeup of the individuals of that group.
Most modern explanations of how weather affects crime, then, rely either on a model suggesting that weather increases the level of interactional stress and pushes our culturally provided adaptations to their breaking point or one that suggests that weather has a role in changing the routine activities and patterns of social interaction, which changes the likelihood of crime. These theories are based on crime and weather data, and they are continually being tested by researchers using ever more detailed and extensive data sets. This research has yielded findings that do seem to be consistent as criminologists examine the impact of weather and season on crime.