This exploratory study describes seasonal variations in selected crimes based on data from the large-scale National Crime Survey for the period 1973-77.
Prepared by the U.S. Bureau of the Census for the Bureau of Justice Statistics, this report considers the applicability of certain factors to explain crime's seasonal variations, such as length of month, school year (its timing with a traditional summer vacation), weather, and amount of daylight. Seasonal influences were particularly evident for household larceny, personal larceny of less than $50, and unlawful entry burglary. Other crimes with less pronounced seasonal patterns were personal larceny of $50 or more, forcible entry burglary, assault, and motor vehicle theft. Personal robbery showed no evidence of seasonal variation. Crimes influenced by seasonal patterns peaked in the summer months and reached their lowest levels in the winter. The exception was personal larceny under $50 which registered its highest point in October and dropped to lows in the summer. When seasonal movements were eliminated from each of the crime series, upward trends were evident in the number of incidents of household and personal larceny of $50 or more and of simple assault, with no clear downward trends. Overall, there is an association between warmer weather and increased crime for most crimes studied. Evidence also suggests that petty larcenies occurring away from home, many of whose victims are school children, peak in the fall at the start of the school year and reach their lowest levels during summer vacation. These and other possible explanations for seasonal changes will be examined more closely in future reports. Graphs and charts support the text. An appendix contains a technical note. (Author abstract modified)