Something appears to be going on with sunroofs, as around 550 complaints of broken sunroofs were filed with the National Highway Traffic Safety Administration (NHTSA) in 2025. This year, the number is already approaching 500. The complaints have involved more than 200 models from 17 manufacturers, with drivers reporting that their vehicles’ sunroofs unexpectedly shattered. However, there is no single confirmed cause for the incidents.

Those numbers come from a report by The Wall Street Journal, which highlighted the unusual circumstances surrounding these incidents. In many cases, there was no obvious warning that the sunroof was about to shatter. The incidents occurred during normal drives, when occupants suddenly heard a loud bang and found thousands of pieces of glass scattered inside their vehicles. Above them was an open roof where the glass sunroof had been moments earlier.

Since 2021, the National Highway Traffic Safety Administration (NHTSA) has received nearly 2,800 complaints involving sunroofs unexpectedly exploding or shattering. One example is Amber Nguyen, whose 2025 Lexus SUV’s sunroof shattered while she was driving on a highway. Fortunately, the sunshade was closed, which helped prevent the broken glass from falling directly on her.

There could be several reasons for sunroofs to shatter suddenly, and there is no single reason that applies to all cases. Road debris could be one possibility. A tiny rock or other object can hit the glass and leave damage that isn’t immediately noticeable, which could later cause the tempered glass to fail. Heat and temperature changes may also put additional stress on the glass.

The growing size of sunroofs could also be a factor. Modern vehicles increasingly have much larger glass roofs, giving debris and other stresses a bigger target. However, manufacturing defects cannot be ruled out and could cause the glass to break after a certain period of time. NHTSA has investigated unexpected sunroof breakage before. In 2013, it opened an investigation after complaints involving Kia Sorento SUVs. The investigation eventually expanded to more than a dozen automakers and identified more than 4,000 reports of sunroof fractures.

But in 2021, NHTSA did not identify evidence of a safety-related defect requiring action. It suggested that things such as small rocks striking the glass could cause imperceptible damage that eventually leads to failure. The agency says it hasn’t identified verified crashes or serious injuries caused by breaking sunroofs, although it continues to monitor and investigate the issue.

The issue is becoming more noticeable partly because sunroofs are now far more common and larger than they were a decade ago. More than 50% of vehicles sold in the U.S. now have sunroofs, compared with about 35% a decade ago, meaning more vehicles now have large glass panels exposed to potential impacts and temperature-related stress.

While road debris may be responsible for some incidents, the exact cause of many breakages remains unclear. The Wall Street Journal report also notes that laminated glass, like that used in windshields, could provide a safer alternative because it is designed to keep broken glass together rather than allowing it to scatter throughout the cabin.