And while staying vigilant while driving should be an everyday habit, experts say some days are simply more dangerous than others for drivers. Counterintuitively, car fatalities tend to peak in the summer months, despite more temperate weather conditions. Experts say that’s because during the summer, roads are more congested, inexperienced teen drivers are on the road in higher numbers, there’s more road construction, and high heat can lead to engine failure, tire blowouts, or other mechanical failure. Put all of this together, and you’ve got a recipe for disaster on the road. So when are the roads considered most dangerous? The Insurance Institute for Highway Safety (IIHS) crunched the numbers using data from from motor vehicle crashes between 2015 and 2019, and has identified the six days of the year associated with the most fatalities. Read on to find out which day of the year is the single deadliest among them. RELATED: This Is the Most Dangerous State in America. Total deaths: 613ae0fcc31ae342fd3a1346ebb1f342fcb Total deaths: 616 RELATED: If You See This While Driving, Turn Around Immediately, CDC Says. Total deaths: 620 Total deaths: 632 For the latest safety news sent directly to your inbox, sign up for our daily newsletter. Total deaths: 645 Total deaths: 655 RELATED: This Is the Most Dangerous City in America.