Violent crime increases during warmer weather, no matter the season, study finds

Interesting. When I read about the rise in the rate of violent crime last year, although it was far from what it used to be, I wondered about changes in age distribution and the nasty political climate. But temperatures are rising and last year was also the hottest year on record.

https://www.eurekalert.org/pub_releases/2017-09/du-vci092517.php

Public Release: 25-Sep-2017
Violent crime increases during warmer weather, no matter the season, study finds
Drexel University

Among police officers, there's a maxim: Being a cop gets a whole lot busier when it's hot out. Now, a study by a pair of Drexel University researchers appears to back them up.

The research, conducted by Leah Schinasi, PhD, assistant research professor, and Ghassan Hamra, PhD, assistant professor, both of Drexel's Dornsife School of Public Health, was published in the Journal of Urban Health and used a decade's worth of crime data in Philadelphia (from 2006 until 2015) to find that rates of violent crime and disorderly conduct increased when daily temperatures are higher.

Overall, crime rates were highest in the warmest months of the year -- May through September -- and highest on the hottest days.

For example, when the heat index (a metric that uses temperature and humidity to represent human comfort) was 98 degrees, rates of violent crime were 9 percent higher compared to days when the temperature was 57 degrees. When it came to rates of disorderly conduct, they were 7 percent higher on 98-degree days than on 57-degree days.

During the year's colder months -- October through April -- the contrast of high versus low rates of crime on more comfortable versus cooler temperature days was more striking. When temperatures reached 70 degrees during that time period, daily rates of violent crime were 16 percent higher, on average, and disorderly conduct rates were 23 percent higher, compared to 43 degree days, the median heat index for that period.

The researchers also looked at deviations of daily temperatures from seasonal averages in trying to determine the effect of anomalies on crime rates. For example, during cool months, days that were 55 degrees warmer than the seasonal average were associated with 7 percent higher rates of disorderly conduct.

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