Every fall in the islands, a familiar pattern unsettles surfers, divers, and coastal communities: shark bites climb just as the trade winds ease and the water stays warm. For years, locals called it “Sharktober” and traded theories about murky water, holiday crowds, or bad luck. Now a new wave of research suggests the October spike is real and closely tied to the life cycle of tiger sharks, not folklore or fear.
By digging into decades of bite records and pairing them with shark tracking and behavior data, scientists have begun to explain why encounters peak in this narrow window. The emerging picture is not of rogue predators, but of large female sharks using the nearshore waters of Hawaii as a nursery and refueling stop at the exact time people are most likely to be in the ocean.
What the numbers say about “Sharktober”
The first step in separating myth from pattern was to look at the long record of shark bites in Hawaiian waters. Researchers compiled incidents from the mid‑1990s onward and found that unprovoked encounters are not evenly spread across the calendar. Of the 165 unprovoked shark bites recorded in Hawaiian waters between January 1995 and October 2024, 32 (20%) occurred in October, a concentration that stands out even after accounting for busy beaches and warm conditions later in the year. That cluster is what gave rise to the local shorthand “Sharktober,” and the data now show the nickname reflects a measurable seasonal bump rather than superstition.
When scientists at the University of Hawai and partner agencies ran statistical tests on the incident record, they confirmed that October produces a significantly higher rate of bites than most other months. A separate analysis of the same dataset, highlighted by Of the 165 incidents, found that roughly one fifth of all bites in nearly three decades were compressed into that single month. For a state that already lives closely with sharks, that seasonal signal is strong enough to shape how lifeguards, tour operators, and residents think about risk in the water.
Why October is different in Hawaii’s waters
To understand why October stands out, I have to start with the sharks themselves. Tiger sharks are the main species implicated in serious bites around the islands, and new tracking work shows that their numbers in nearshore waters rise sharply in early fall. Ecotourism operators and researchers report that Tiger shark numbers are highest off the main islands in October, which means more large predators are cruising the same reefs and channels that swimmers and surfers use.
Scientists now link that seasonal influx to reproduction. Female tiger sharks are believed to give birth in late summer and early fall, and several teams, including those behind the Shark bite analysis in Hawaii, argue that parturition is the key. As Dr. Meyer and colleagues explain, the process of giving birth and then rebuilding energy reserves appears to draw big females closer to shore, where prey is abundant and currents are calmer. One report notes that these sharks are actively feeding to recover energy reserves in the weeks after they pup, which lines up almost perfectly with the October spike in bites documented in the long‑term records.
The science behind “Sharktober”
The phrase “Sharktober” started as surf‑line slang, but it has now been adopted by researchers who have tested whether the pattern holds up under scrutiny. A Sharktober briefing from the New University of Hawai team describes a statistically significant increase in tiger shark bites in October, confirming what lifeguards and fishers had been saying for years. A companion release from the New University of group emphasizes that the goal is not to stoke panic, but to use the seasonal signal to improve awareness and coexistence without sensationalism.
In their technical summary, the same researchers stress that understanding when risk is slightly elevated can help people make informed choices about ocean use. They point out that the October spike is real, but the absolute numbers remain low compared with the millions of annual ocean entries around Hawaii. Coverage in local media, including a STAR and ADVERTISER report on a warning sign off Haleiwa, has echoed that balance, highlighting the October pattern while reminding readers that fatal attacks remain rare.
Birth, feeding, and the mechanics of risk
The most intriguing part of the new research is how it ties shark behavior to the timing of bites. A multi‑decade analysis of incidents, described in a Frontiers in marine science summary, concludes that shark attacks are most likely to happen around the time the animals are giving birth. By Stephen Beech, one account of the work notes that the incidents cluster when large females are nearshore to pup and then hunt intensively, which increases the odds of a mistaken bite on a surfer or swimmer. Another version of the same findings, also By Stephen Beech, underscores that the October spike lines up with this reproductive window.
Dr. Meyer, whose work is cited in several of the reports, argues that parturition and post‑birth feeding create two overlapping pathways to more shark‑human encounters. First, giving birth to a litter of pups brings big females into shallow, protected areas that are also popular with people. Second, the need to rebuild energy reserves after pregnancy pushes those same sharks to feed more actively on turtles, fish, and other prey close to shore. In one Meyer interview, he links this intense foraging to the sharp rise in the bite record, while another Meyer briefing advises people to be aware that large tiger sharks are more likely to be present in the nearshore waters of the Main Hawaiia islands when the animals are in this reproductive and recovery phase.
How people are adapting to a predictable spike
Once you accept that October carries a slightly higher risk, the question becomes how to respond without demonizing sharks or emptying the beaches. Scientists in Hawaii who helped document Sharktober’s seasonality have been clear that the answer lies in targeted awareness, not blanket fear. Their guidance, echoed in a Sharktober explainer, includes simple steps: avoid murky water, stay out of the ocean at dawn and dusk when visibility is low, and give extra thought to location and conditions in October if you plan to surf or dive in known tiger shark areas.
Officials and researchers are also refining how they communicate risk. A detailed release from the New University of team stresses that the goal is coexistence, not culling, and that better information can help residents and visitors keep perspective. Another statement from the same group, which notes that Understanding when risk is slightly higher allows people to make rational choices, frames the October spike as a manageable seasonal feature of life in the islands. A related Sha update, issued with support from the state Department of Land and Natural Resources, reinforces that message by tying public advisories to the same reproductive and feeding patterns that scientists have now mapped in detail.
For visitors planning a fall trip, the takeaway is not to avoid the ocean, but to treat October the way mountain communities treat avalanche season: a time for extra attention, not paralysis. The long record of 165 bites over nearly thirty years, with 32 in October, shows that serious incidents remain rare in a place where millions of people enter the water every year. As more data from the Hawaii tiger shark studies and related Key Points analyses filter into public guidance, the hope among researchers is that a clearer picture of Sharktober will replace fear with informed respect for the predators that have patrolled these waters far longer than any surfer lineup.
