A large winter storm system affected much of the central and eastern United States over the weekend, with Swiss Re warning of the peril's increasing loss potential as heavy snow, freezing rain and dangerously cold temperatures struck multiple regions.
The storm produced snowfall totals exceeding 12 inches in parts of the Midwest, Mid-Atlantic and Northeast. Ice accumulations in portions of the southern US resulted in downed trees, power outages and hazardous travel conditions.
Winter Storm Fern, which swept the US recently, is expected to generate insured losses "well into the billions of dollars," according to analysis from Howden Re. Fern affected more than 220 million people across at least 34 states, bringing cold and ice over much of the same population impacted by Winter Storm Elliott in December 2022.
The pattern highlights a defining characteristic of winter storms: their ability to affect large populations and multiple economic sectors simultaneously. Regions with varying levels of cold-weather preparedness face exposure to the same event.
Within catastrophe risk frameworks, winter storms are classified as primary perils alongside hurricanes and earthquakes. Their broad geographic footprint, multi-day duration and interaction with exposed infrastructure mean that even moderate events can generate substantial aggregated losses.
Balz Grollimund (pictured above), head of cat perils at Swiss Re, said insured losses from winter storms have risen in recent years. "Between 2021 and 2025 the average annual insured loss in the U.S. has been more than US$7 billion (2025 prices) compared to around USD 2 billion between 2011 and 2020 (2025 prices)," Grollimund said.
Swiss Re said extreme cold, rather than snowfall or wind alone, has been the dominant driver of the largest winter storm losses. Prolonged freezing temperatures increase the likelihood of widespread pipe failures, water damage and business interruption, particularly when combined with power outages.
The February 2021 Arctic outbreak in the south-central US illustrated how infrastructure stress can amplify losses, transforming a cold-weather event into a systemic insurance loss. The December 2022 freeze affected more than 40 US states simultaneously and generated losses across multiple lines of business.
The upward trend in winter storm losses reflects more than weather variability, according to Swiss Re. Asset accumulation, urbanization, rising construction and repair costs, and increasingly interconnected infrastructure systems are amplifying loss potential.
