Social videos show the Denver-area hailstorm on May 9 that has turned out to be Colorado's most expensive storm ever. (The Washington Post)

On May 8, a monster thunderstorm rolled over the Denver metro area during the evening rush hour. It dropped baseball-size hail on unsuspecting commuters and piled up on the highways like snow.

Seeing photos and videos of the destruction on social media, we knew then that it was going to be a very expensive storm. Now, given the number of claims filed for damaged cars and homes, the storm is going to be “Colorado’s most expensive insured catastrophe,” at $1.4 billion, according to the Rocky Mountain Insurance Information Association.

“This storm would surpass the $845.5 million July 20, 2009, storm and the July 11, 1990, storm, the most expensive in adjusted costs for today’s dollars,” the association wrote in a news release.

The largest hailstone reported to the National Weather Service was 2.75 inches in diameter in Wheat Ridge just west of Denver, but we’ve seen photos of what look like larger stones — namely this softball-size rock of ice that fell on the campus of Metropolitan State University of Denver. That’s the kind of hail that busts through a windshield like it’s tissue paper.

On top of all this, it happened during the evening rush hour when there were hundreds of thousands of cars out on the roads instead of tucked safely in their garages.

The insurance group estimates more than 150,000 auto insurance claims and 50,000 homeowner insurance claims will be filed.

It’s not unheard of for hailstorms to cause incredible insurance losses. In April this year, a hailstorm in San Antonio resulted in $1.4 billion in losses and became the costliest hailstorm in Texas history, unadjusted. Car damage was estimated at $560 million, and damage to homes was around $800 million, according to the Insurance Council of Texas as reported by the San Antonio Express. More than 110,000 vehicles were damaged by the storm.