With the seemingly endless summer in Southern California and a very hot autumn this year, should we be more concerned about crime? Everyone knows that crime increases in hot weather, right? Well, not so fast. Several studies have disputed that oft cited axiom.

Statistics for Los Angeles homicides show that the murder rate is highest in July and August, but almost as high during the cooler months of December and January.   In New York City, the Wall Street Journal conducted a study in which seven index crimes—murder, rape, robbery, felony assault, burglary, grand larceny and stolen vehicles— were reviewed month-by-month. The crimes were indexed by month for the years 2007 through 2009. The study found that New Yorkers are about as likely to be a victim of crime in the cold month of December or the cool month of October as they were in the hot summer months. A study on New Orleans shootings from January 2011 to June 2015 found virtually no relationship between hotter outside temperatures and the number of shootings.

Other studies have had mixed results. A comprehensive study involving violent crime over a two-year period in Minneapolis, Minnesota concluded that violent crime did rise with temperature, but only up to about 80 degrees Fahrenheit; above that temperature, the rates started to fall. A similar result was found in a Dallas, Texas study. There the researchers investigated whether there is a relationship between outside temperatures and violent crime. The results of that study indicated that there was a positive and increasing relationship between temperature and violent crime but after the mercury hit 80 degrees Fahrenheit the relationship moderated and actually turned negative when the mercury went beyond 90 degrees. The Minneapolis and Dallas researchers both hypothesized that higher temperatures encourage people to go indoors where it is cooler thus decreasing the opportunity for crime.

On the other hand, there are numerous studies and crime statistics that suggest criminal activity does indeed increase during the hot summer months. The explanations for this increase in crime are as varied as the crimes themselves. Many make the common sense assumption that heat makes “hot-heads.” When people are sweltering, their tempers go up. There might be some truth to this as many of us need only look to our personal experience to confirm that heat can cause some people to anger quicker.

Summer crimes might also increase because the opportunities for crime increase. During summer months, people leave their windows open more often and are away from home during the summer vacation months. Also, more people are outside, which creates the opportunity for more confrontations. Others have observed that since most schools are not in session during the summer months, more youths are on the streets and the under-25 year old crowd commits more crime than those who are over 25.

The conclusion that crime rates go up with rising outside temperatures may be partially true but there is little evidence that the increase in crime is caused by the hotter temperatures. It is more likely that a variety of convergent factors influence the crime rates in hot weather.