Hurricane Helene struck communities that had been considered relatively safe from extreme weather. The storm exemplifies a pattern that has emerged as climate change has intensified: catastrophic weather events can happen anywhere.
Hurricane Helene carved a path that shocked many people. The storm left a wake of devastating damage on the Gulf Coast of Florida, up through Georgia, and into regions of Tennessee and North Carolina in the Appalachian Mountains.
A hurricane that causes catastrophic damage several hundred miles from the coast looks like an anomaly. Tropical storms can have impacts far from the coast, but the extent of the damage as far away as Asheville, North Carolina—nearly 500 miles from where the hurricane made landfall—seems unprecedented. People have moved to the region in recent years, mainly to vibrant cities like Asheville, in part to escape the worst of climate change. Asheville, which had been seen as a “climate haven” and largely immune to the most serious manifestations of climate change, has experienced significant population growth over the past two decades.
So, was Hurricane Helene an anomaly for southern Appalachia? In a recent series of blog posts, we chronicled the trends and spatial patterns of extreme weather events like Helene in the United States from 1995 to 2022. To answer this question about anomalies, we revisited our data for the counties in Georgia, North Carolina, and Tennessee that Helene seriously impacted, so we could evaluate the history of extreme weather in these counties over this 28-year period.
As background, our blog posts were based on a county-level data set that we created using the Storm Events Database, which is maintained by the National Weather Service, an arm of the National Oceanic and Atmospheric Administration. The National Weather Service records the location and timing of every extreme weather event that occurs in the United States, along with an estimate of the property damage, crop damage, fatalities, and injuries from each event. Events fall into approximately 50 individual categories in the raw data; we aggregated these 50 into 8 broader categories: drought; flood; heat; hurricane; thunderstorm, wind, or hail; tornado; wildfire; and winter weather. The raw data also contain various kinds of location information: sometimes latitude and longitude, sometimes county, and sometimes a forecast zone specified by the National Weather Service. From these raw data, we created a data set that contains the year, month, and category for every extreme weather event in every county in the United States from 1995 through 2022.
Forty-five counties in Georgia, North Carolina, and Tennessee had major disaster declarations associated with Helene as of October 4. A few significant findings about the history of extreme weather events in those 45 counties stood out.
The average number of hurricane and flood events in the 45 counties from 1995 to 2022 is about equal to the average across all counties in the United States (coastal and inland) during that time period. This average is about 2 hurricanes and 25 floods.
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However, the average property damage from extreme weather events of all types was significantly smaller in the 45 counties than in the average US county: $18.8 million in the 45 counties compared to $123 million across all counties. (Note that the data from the National Weather Service include only direct property damage and not indirect costs, such as interruptions to business activity, which tend to significantly increase the total cost of disasters.) This finding indicates that past storms have not been as catastrophic in the Appalachian region as in most other parts of the country.
Even on a per capita basis, property damage in these 45 counties was significantly smaller than the national average: $390 versus $3,112.
Of the 45 counties that saw major damage from Helene, only 1 experienced property damage and per capita property damage between 1995 and 2022 that was above the US average. This was Haywood County, North Carolina, which incurred about 90 percent of its damages during Tropical Storm Fred in 2021.
Over the 28-year period, the 45 counties collectively saw 84 deaths that were directly caused by extreme weather events. As of October 7, 2024—ten days after Helene made landfall—over 230 deaths have been attributed to the storm, and most of these deaths occurred in the mountains of Georgia, North Carolina, and Tennessee.
In sum, the data suggest that Helene indeed was an anomaly. To investigate further, we turned to one more source of data, the Weather Variability Explorer (WeaVE) maintained by Resources for the Future. WeaVE includes various measures of temperature and precipitation variability. We looked at the data in WeaVE for extreme one-day precipitation. This measure is the percentage of annual rainfall in an area that occurs on days that are in the 90th percentile of precipitation for the year, i.e., the high end of the distribution. High percentages indicate that an area gets relatively more of its annual rainfall in a short amount of time. This intense rainfall can be a problem, overwhelming infrastructure and leading to flooding, which is exactly what happened during Helene: between 13 and 31 inches of rain fell at locations in western North Carolina over a two-day period.
On average, the extreme one-day precipitation figure was 19.4 percent across all US counties over the last three years. But in the 45 counties that were most impacted by Helene, the average was 15.9 percent. So, the data on extreme precipitation, like the historical data on extreme weather events, suggest that Helene was an anomaly for southern Appalachia.
Communities Everywhere Need to Prepare for Disasters and Build Resilience to Climate Change
Yet anomalies might not be so anomalous after all. The very nature of extreme weather events is that they are rare; they fall in the tails of the probability distribution. In our national analysis of the data on extreme weather events, we took a careful look at the 15 counties in the United States that experienced the most property damage from bad weather between 1995 and 2022. What we found was this: Many of the counties on the list experienced almost all of their damage in a single event. For example, Butte County, California (population 207,000) ranks third due to a single event—the Camp Fire of 2018, which decimated the town of Paradise. Monmouth County, New Jersey, ranks fourth, incurring 99 percent of its damage from Hurricane Sandy in 2012.
These findings suggest that communities cannot let history be their guide when planning for disasters, and no truly “safe” havens from climate change may exist.
Haywood County, North Carolina, developed additional protocols for emergency services following large losses from Tropical Storm Fred three years ago, and the county appeared to be the most adept in the region at issuing warnings and facilitating evacuations in the lead-up to Helene. Other counties, which largely were spared from Fred, turned out to be much less prepared to act. This contrast suggests that a lack of disasters in the history of a region might bring a false sense of security.
In addition to building emergency preparedness, communities must find ways to build resilience to climate change. Resilience includes critical investments in infrastructure such as roads, bridges, dams, and levees that account for more extreme weather in design standards; residential building codes that ensure homes are constructed to withstand weather extremes; local zoning codes that account for risk in guiding where land is developed and people live; and improved communication and disclosure of risk.
Hurricane Helene has shown us that these are problems that require attention from not just large, coastal cities, but also small, rural communities that often have limited staffs in local government, a small property-tax base, and other pressing concerns they need to address with limited resources. In the coming years, placing more focus on policies that help these communities navigate competing needs, while strengthening their ability to survive unexpected catastrophes, will be imperative.
