Over the past seven days, America has witnessed three mass shootings that left four dead and 16 injured. These attacks bring the US mass shooting bodycount so far in 2016 to 103 dead and 353 injured in 94 incidents. Europe, meanwhile, witnessed zero mass shootings, holding the continent's toll in such attacks to date this year steady from last week's count at 14 incidents that left 13 dead and 55 injured.This week's American mass shooting body count was the lowest in a month. A marked departure from the grueling toll of the last few weeks, the relative lull seems at first glance to contradict predictions that a bloody April was just the start of America's killing season—a rash of violence invited by the warmer weather of spring. Yet experts on gun violence epidemiology say we can still expect a long-term increase in such attacks over the coming months, even if it's punctuated by the occasional light week.Observers have long believed in the power of warm weather to increase gun violence, suggesting that the heat of summer especially raises people's heart rates, changes their metabolisms, and increases testosterone levels, giving a boost to rage and rampages. But such physiological theories face heavy challenges; they can't really explain bloody streaks in a breezy April, for instance.Yet experts still tend to note spikes in general and specifically gun violence alike beginning in the spring. Some tend to claim that the increase is simply a result of warm weather drawing people out of winter hibernation in their homes, bringing more potential shooters into contact with more potential victims.This doesn't change the fairly random nature of mass shootings, according to James Fox, a professor at Northeastern University specializing in mass murders and gun violence. But the weather may bolster the odds of someone with a gun coming across someone else he or she wants to shoot. It also probably increases the chance that when bullets fly into a crowd, they might injure a significant number of people. "The lifestyle changes that occur with warmer weather create more opportunities for [mass shootings] to happen," Fox explains, summarizing the grim equation.This logic may help explain why several of this week's mass shootings were bloodier than similar events earlier in the year. To wit, at about 9:00 PM Wednesday, a shooting on the street in Minneapolis, Minnesota, killed one and injured seven. Later that night, around 1 AM, an ambush on a card game in a tire shop garage in Shreveport, Louisiana, killed two and injured six. Then, at 9 PM Thursday, a final shooting outside a housing complex in Allapattah, Florida, killed one and injured three.In previous weeks, shootings at groups on the street often killed or injured no more than four or five people. It's hard to prove, but there's a chance warmer spring weather brought more people out to the deadly gatherings—or their vicinity—in Minneapolis and Shreveport this week, inflating the bodycounts.Just as it's hard to show a clear link between weather and increased death or injury in a single event, it's hard to predict exactly how many more mass shootings spring will bring. These tragedies are still ultimately governed by randomness and chance. But there's reason to believe we may see a rising tide of mass shootings in aggregate, some of them with escalated death tolls, just in time for summer.Follow Mark Hay on Twitter.
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