It's spoken as a general truth in Chicago: As temperatures rise, so does the crime rate.
On its face, it seems fact. In the past two weekends, 75 people were injured in shootings in Chicago and 11 were killed while temperatures spiked to 81 and 93 degrees. On Memorial Day weekend, the first 90-degree weekend of the year, 41 were hurt in gunfire and 10 were killed.
Ahead of another scorcher, will Chicago lose its cool again? Northwestern Memorial Hospital's emergency room is prepared for it with a higher number of trauma doctors and nurses during summer months.
"It is true that when the weekend is very hot, we do have an increase amount of traumas: shootings, stabbings and motor accidents," said Dr. Rahul Khare, an emergency medicine physician at Northwestern.
Whether that's a coincidence is up for debate. In the past two years, reports of violence tended to rise on weekends when temps rose into the 80s, according to statistics pulled from the National Weather Service and reports of weekend shootings.
"It's a little more complicated than that," said Tracy Siska, executive director of the Chicago Justice Project, which independently evaluates urban criminal justice agencies. "But the weather definitely plays a role."
Siska said heat forces more people outside, which causes more interactions, and that causes more opportunity for potential violence. In communities with no air conditioning, even more people are hanging out in the street, he says, and it leads to more interaction.
That's how Pat Camden, spokesman for the Fraternal Order of Police, sees it too. Anecdotally, he says, police see more violence on a hot weekend, but the same goes for nights when the moon is full.
"If you have enough manpower you try to put the resources where you can," Camden said.
Siska says he'll agree to disagree on the full moon comment that police officials have used in the past to stave off hot weather connections to violence.
"It's hard," he said. "Is the weather a cause? No. Is it a contributing factor? Yes."
The Chicago Police Department's new "Violence Reduction Overtime Initiative" starts in full force this weekend, offering overtime pay to officers who work extra hours in neighborhoods where crime is highest.
The new incentive lets officers work straight through weekends and furloughs for time-and-a-half or comp time.
That program correlates with crime rates, though, and not the weather. Camden said temperature doesn't change the amount of manpower from weekend to weekend.
"The bottom line is you have more people outside and more opportunity for crime," Camden said. "Does the weather cause the crime? ... It's very difficult to say."