It’s a sentiment so common it’s become cliche: The mercury starts rising and the crime rate does, too.
A week into summer, Philadelphia has already experienced spikes in both, with temperatures reaching 97 degrees and at least 24 injured – five fatally – in 15 separate incidents of violence between Saturday and Tuesday morning alone.
“Historically, the summer months have been most problematic, beginning around April when it starts to warm and continuing, in most cases, to October,” Deputy Police Commissioner Kevin Bethel confirmed, adding that shootings and homicides seem to be the crimes most affected by the season.
According to Philadelphia police statistics, there were 86 fewer violent crimes during the week ending January 22, 2012, when the average high temperature was 40 degrees, than this past week ending June 24, when the average high was 88 degrees – a reduction of nearly 25 percent.
Veteran criminologist Ellen Cohn, who has been studying the temperature-crime connection for over 30 years, said it is not specific to Philadelphia. “We’ve done different studies in different states and countries – I’m working with a colleague in New Zealand using data from South Africa and we’re still seeing a correlation there,” she said.
“We’ve studied a number of other weather variables – rain, snow, air pressure, humidity – sometimes they show a relationship, sometimes they don’t. Temperature is very consistent, though.”