Study: Warm Weather Is a Factor in Increased Road Deaths

A study investigating deaths from car crashes found a correlation between warmer weather, vehicle miles traveled (VMT), and, ultimately, deaths on the road. Conducted by Dr. Leon Robertson, formerly of Yale University, the study found that 2015 was a particularly warm year in the U.S. and suggests this might be why it was such a deadly year on the streets. "Road deaths in the U.S. jumped 7 percent in 2015, to 35,200 — an abrupt reversal of the downward trend that has persisted for the previous 35 years," Susan Perry writes in the Minneapolis Post.

Robertson undertook the study in part because he was not convinced by the hypothesis that the jump in deaths was attributable to distracted drivers with cell phones. Robertson points out that by 2014 cellphones were already ubiquitous in the U.S.

"[Robertson] found that for each degree increase in temperature, vehicles were driven an average of 60 extra miles per person per year. He also found that for each additional inch of rainfall, vehicles were driven an extra 66 miles per person," Perry reports. Still, this study can only show correlation (not causation) between weather and driving, especially since the participants were not surveyed.