Vast numbers of people have rushed to evacuate from at-risk communities in Florida as the state prepares for Helene, a monster storm system that’s expected to make landfall as a Category 4 hurricane.

Hurricane Helene is expected to drop up to 15 inches of rain in some areas, and could cause storm surge of up to 20 feet in places. Winds may exceed 156 miles per hour. “This is not a survivable event for those in coastal or low-lying areas,” cautioned Jared Miller, the sheriff of Wakulla County, located in Florida’s Big Bend region where the storm is expected to make landfall.

Helene has not yet made landfall, but heavy rain, flooding, and strong winds were already damaging Florida communities on Thursday.

In Hurricane Helene’s Path

Population dynamics data from Meta’s Data for Good indicate that many in danger’s path are choosing to evacuate. Using anonymized data, CrisisReady, a research-response initiative at Harvard and Direct Relief, recorded areas with increase and decrease of population in the hours and days prior to Helene’s landfall. For example, St. George’s Island off the Florida coast registered a population decline of 92% on Wednesday evening. Coastal areas from Lower Grand Lagoon to Apalachicola show declines of 25 to 50%.

Although tropical storms are extremely common in Florida, Hurricane Helene poses an extraordinary danger. In addition, Helene’s path is similar to that of Hurricane Idalia, which battered the Big Bend region last year. Idalia’s impacts were widespread and severe, and some communities threatened by Helene are still in recovery.

Andrew Schroeder, Direct Relief’s Vice President of Research and Analysis, noted that there was a significantly higher incidence of movement away from coastal towns rather than inland areas. In the small town of Steinhatchee, for example, which experienced up to 12 feet of storm surge during Idalia, population data showed a 53% decrease.

Shelters were open and receiving evacuees on Thursday, as a state of emergency was active in 61 of Florida’s 67 counties.

Evacuations cause urgent health needs as people flee without lifesaving medications and medical devices, shelter together in close quarters, and experience trauma — a mental health danger that evidence shows is compounded by repeated exposure to natural disasters.

But evacuation is not always straightforward. Population dynamics data indicate a change in the number of people occupying an area — although Schroeder notes the correlation is somewhat lower in rural areas than urban ones — but it does not track the movements of individuals, and sometimes the data offer surprises.

As an example, Schroeder pointed out that Citrus County, currently bracing for dangerous storm surge, was registering a 12% population increase. The county has the oldest population in this area of Florida — 36% of residents are over 65 years old —and the highest percentage of people who use powered medical devices.

“That’s a pretty high vulnerability,” he said. A storm like Helene can knock out power for days, causing serious risks to people who rely on electricity to power devices.

Many people in high-risk counties will not evacuate, Schroeder said, and not everyone should. Although administrative divisions like cities and counties are useful for determining emergency measures and communicating information, the danger isn’t equal everywhere, and local guidance will vary.

But not everyone who would be safest evacuating will do so — often because they’re not able to do so. While Direct Relief’s Research and Analysis team noted that 1.9 million people in Florida, Alabama, and Georgia are threatened by hurricane-force winds connected to Helene’s storm system, more than 343,000 of those people are below the federal poverty line — about 18%. A lack of financial resources — along with disabilities and mobility issues, language barriers, and other social determinants for health — make it much more difficult to evacuate, and decrease the likelihood that someone will do so.

Federally qualified health centers and other first responders often describe the most urgent need in the aftermath of a storm coming from people who had no choice but to ride out the storm at home. Health center staff have described people in dire need of food, clean water, tetanus vaccines, wound care, and replacements for medications like insulin — which need to be delivered through flooded streets.

Direct Relief-funded mobile medical units and emergency response vehicles often fill these needs, navigating streets filled with debris and lingering floodwaters to care for patients endangered by the storm and its aftermath.

Health Risks and Displacement

Whether people evacuate or shelter in place, hurricanes and other extreme weather events have severe and long-lasting impacts on health.

Chronic diseases like diabetes and hypertension can spiral out of control in the aftermath of a major disaster, as care and access to medicines are interrupted. Shelter settings cause outbreaks of Covid-19, diarrheal disease, and other infectious illnesses. Water-borne diseases, physical injury, and tetanus threaten health as people return to flooded communities, clear damage, and begin to rebuild.

Post-traumatic stress, depression, and anxiety are a long-term threat as well, affecting new people and increasing the severity of existing conditions. New research is emerging that people in storm- and wildfire-prone areas, exposed to repeated threats, evacuations, and impacts over time, are particularly likely to experience compound effects.

Direct Relief’s Response

In preparation for these events, Direct Relief equips health centers throughout tropical storm-vulnerable regions with hurricane preparedness packs, large-scale modules stocked with the medications and medical supplies most commonly needed in the aftermath of an extreme weather event. Several of these HPPs are within or near Hurricane Helene’s projected path.

Within the past two weeks, Direct Relief delivered 10 shipments of essential medicines and supplies to six partners located in the storm’s projected path as part of the organization’s ongoing safety net support program. The program supplies community health centers, free and charitable clinics, and charitable pharmacies with medical support, which is used to treat low-income and uninsured patients and ensure greater resilience.

The organization will assess needs and potential response measures stemming from Hurricane Helene in the coming days. Transportation support and medical procurement, emergency medical backpacks, hygiene kits, new hurricane preparedness packs, and emergency grants are all frequent priorities in the aftermath of a tropical storm.