A weather expert countered that it was unclear whether severe hail had significantly increased in the United States over the long term. Harold Brooks, senior research scientist at the National Severe Storms Laboratory, which is also part of NOAA, said the storm prediction center’s hail data should be viewed with caution.

Reports, for instance, can be submitted by volunteer spotters whose training may vary. (Typically, people reporting hail are asked to compare it to the size of a ball or coin, which is then translated into a measurement in inches.) Also, the criteria for severe hail was changed in 2010, making historical comparisons challenging.

Still, insurers are reporting bigger hail losses. In 2023, State Farm paid 27,300 claims for hail damage to homes and businesses, up from 23,200 in 2022, said Heather Paul, a company spokeswoman. Payouts totaled $6.1 billion last year, more than the previous two years combined.

“We’re seeing severe weather increase,” Ms. Paul said.

In addition, inflation is driving up the cost of materials and labor to repair the damage, increasing insurers’ liability. More development in areas affected by severe storms is also a factor. State Farm’s average homeowner hail claim last year was about $17,000, up from $16,000 in 2022, Ms. Paul said.

That’s a worrying trend for homeowners because losses mean insurers may get “bold with nipping and tucking of coverage,” said Amy Bach, executive director of United Policyholders, a consumer advocacy group. Property owners and insurance adjusters have suggested that insurers are “getting aggressive” in denying hail claims, she said.