Temperature and aggression: effects on quarterly, yearly, and city rates of violent and nonviolent crime.

The hypothesized relation between uncomfortably hot temperatures and aggressive behavior was examined in two studies of violent and nonviolent crime. Data on rates of murder, rape, assault, robbery, burglary, larceny-theft, and motor vehicle theft were gathered from archival sources. The first three crimes listed are violent; the latter four are less violent (labeled nonviolent). On the basis of previous research and theory (Anderson & Anderson, 1984), it was predicted that violent crimes would be more prevalent in the hotter quarters of the year and in hotter years. Furthermore, it was predicted that this temperature-crime relation would be stronger for violent than for nonviolent crime. Study 1 confirmed both predictions. Also, differences among cities in violent crime were predicted to be related to the hotness of cities; this effect was expected to be stronger for violent than for nonviolent crimes. Study 2 confirmed both predictions, even when effects of a variety of social, demographic, and economic variables were statistically removed. Theoretical and practical implications are discussed.