Cold Water Shock & Open-Water Swimming Deaths in the United States
Introduction
Every spring, as the first warm weekend arrives, Americans head for the water. The air feels like summer. The water does not. Across the United States, lakes, rivers and reservoirs in April, May and June routinely sit in the 40s and 50s Fahrenheit — cold enough to cause an involuntary gasp, a racing heart and a loss of muscle control within seconds. That reaction is called cold water shock, and it kills strong swimmers before they ever get tired.
To find out how big the problem is, FutureWristTech analyzed every accidental open-water drowning recorded in the United States over the five years from 2020 to 2024 — the deaths that happen in natural water such as lakes, rivers, reservoirs and the ocean (ICD-10 cause-of-death codes W69 and W70), excluding swimming pools and bathtubs. We pulled the federal cause-of-death records from the CDC's WONDER database for all 50 states, broke every death down by the month it occurred, then matched the pattern against spring water temperatures and real 2024–2026 cases reported by local news, coroners and state agencies.
The finding is consistent from coast to coast: open-water drowning is not just a summer problem. A disproportionate share of deaths lands in the cold weeks of spring, and in the northern states the spring concentration is extreme. Here is what the data shows.
Key findings at a glance
Every number below is drawn from the full 50-state dataset.
The findings in depth
1One in three open-water drownings happens in spring, not summer
Public water-safety messaging is built around summer — the Fourth of July, the long August weekend, school holidays. But the cold-water-shock hypothesis predicts an earlier danger zone: the spring weeks when air temperatures climb but water has not caught up. We tested it by tagging all 10,000-plus open-water deaths from 2020–2024 with the month each one occurred.
Across the 47 states with month-level data, 3,468 of 10,192 open-water drowning deaths — 34% — occurred in April, May or June. If deaths were spread evenly across the year, those three months would account for just 25%. Spring is carrying a third of the annual toll before the official swim season even begins.
The gap between a 25% baseline and a 34% reality is the fingerprint of cold water. In spring, the people entering the water are not reckless — they are responding to warm air. What they cannot see is that a lake still in the low 50s will trigger an involuntary gasp reflex on immersion, and that cold muscles fail within minutes. Knowing the water temperature before you get in is the difference between a swim and a statistic.
2In the northern states, spring is overwhelmingly the deadliest season
If cold water is the driver, the effect should be strongest where spring water is coldest and snowmelt feeds the rivers — the northern tier of states.
The pattern is stark. North Dakota records 60% of its open-water drownings in April–June; South Dakota 54%; Utah 44%; Colorado 42%; Wisconsin 38%. These are not warm-water states having a bad summer — they are cold-water states losing people in spring, when snowmelt-fed lakes and rivers are at their most dangerous and least expected.
The northern states also log the clearest cold-water cases. Montana's Fish, Wildlife & Parks warns that water is still very cold in July and can kill in mere minutes. Colorado Parks and Wildlife states plainly that most water-related deaths involve people swimming in cold water. The data and the agencies agree.
3The raw death toll is largest in the warm-water states — but the timing is different
A fair study separates volume from rate from timing. We ranked states three ways.
By sheer numbers, California (1,012 deaths), Florida (986) and Texas (895) lead over five years — a function of large populations and year-round access to water. But their deaths spread across the calendar: California logs 30% of its open-water drownings in spring, Florida just 28%. The cold-water-shock signal is weaker where the water is warm.
This is exactly what makes the spring finding credible rather than an artifact. Where water stays warm, deaths track the summer crowds. Where water stays cold into June, deaths pull forward into spring. The season follows the thermometer, not the calendar.
4Per person, the deadliest states are cold, remote and water-rich
Rate per 100,000 residents controls for population and shows true per-person risk.
Hawaii (1.9 per 100k), Alaska (1.5) and Montana (1.4) top the table — small-population states where life is lived beside cold ocean, fast rivers or glacial lakes. Alaska's all-setting drowning rate is the highest in the nation at roughly 7 per 100,000, nearly six times the U.S. average, and three-quarters of those deaths are in natural water.
Hawaii is the exception that proves the rule: its toll is ocean- and snorkeling-driven in warm water, not cold-water shock. Alaska and Montana are pure cold-water risk. The lesson for a swimmer is that national averages hide enormous local variation — your state, your lake and your month matter far more than the headline number.
5Cold water shock is named, by officials, in real cases every spring
Cause-of-death codes record drowning, never cold water shock — so the mechanism is invisible in the federal data. To surface it, we read local reporting and official statements on 2024–2026 open-water deaths.
In nine states, police, coroners, park rangers or state agencies explicitly blamed cold water. In Washington, Renton police warned of cold water shock after a 26-year-old drowned in a mid-50s°F Lake Washington. In Nevada, officials issued a cold-water-shock warning the same spring a 25-year-old died at Lake Tahoe. In Idaho, a 14-year-old drowned in March in water reporting described as dangerously cold. In Oregon, a 21-year-old jumped into the 37°F Blue Pool and did not resurface.
These are the faces behind the percentage. Every one was a person who misjudged the water because the air felt fine. That is precisely the failure cold water shock exploits — and precisely why the temperature of the water, not the weather, is the number that should decide whether you get in.
The complete 50-state table
Open-water drowning deaths (ICD-10 W69 + W70), by state of residence. Cold-belt states are shaded blue; a spring share of 40%+ is flagged coral.
| State | Signature water body | 5-yr total | Latest yr | Rate /100k | Apr–Jun % | Spring temp | Rank |
|---|---|---|---|---|---|---|---|
| Loading… | |||||||
Dashes mark figures a state does not publish or that CDC suppresses for counts under 10. Rank is the national rank by overall drowning rate (1 = highest).
State by state: the data and the human cost
Each card carries that state's full dataset alongside the real 2024–2026 case that put a name to the number, and the key finding from that state's own agencies. Editors are free to quote any of it with a link to FutureWristTech.
Methodology
Death counts. Open-water drowning deaths were drawn from the U.S. Centers for Disease Control and Prevention's WONDER database (Underlying Cause of Death, 2018–2024 Single Race file), filtered to ICD-10 external-cause codes W69 (drowning and submersion while in natural water) and W70 (drowning and submersion following a fall into natural water), by state of residence. These two codes capture lakes, rivers, reservoirs and the ocean and exclude swimming pools (W67–W68) and bathtubs (W65–W66). Data were queried on October 21, 2026.
Five-year totals cover 2020–2024. The latest year column is 2024 (2023 for Utah, where 2024 was suppressed). Crude rates are per 100,000 residents as reported by CDC WONDER. Counts below 10 are suppressed by CDC for privacy and shown as <10; the six affected states (Delaware, North Dakota, Rhode Island, South Dakota, Vermont, Wyoming) retain their five-year totals where those clear the threshold.
Seasonality. Each death was assigned to its month of occurrence, and the April–June share was computed as spring deaths divided by the state's five-year total. The national figure aggregates the 47 states with month-level data available. The 25% baseline is the share three of twelve months would represent if deaths fell evenly across the year.
Water temperature. Representative April–May surface temperatures for each state's signature open water were taken from NOAA buoys and the National Weather Service, the U.S. Geological Survey, the National Park Service and state natural-resource agencies. Where only a single-day reading was available, it is labeled as such in the dataset.
Named cases. The 2024–2026 incidents were identified from local news reporting, coroner statements and state-agency releases. A case is flagged as cold-water-related only where police, a coroner, a park ranger or a state agency explicitly cited cold water or cold-water shock; watercraft and paddle-sport deaths were excluded from the open-water swimmer count.
Citation. Centers for Disease Control and Prevention, National Center for Health Statistics. National Vital Statistics System, Mortality 2018–2024 on CDC WONDER Online Database. Accessed October 21, 2026.
Frequently asked questions
About FutureWristTech
FutureWristTech builds affordable, honestly specified dive watches for people who actually get in the water. Our catalog is built on verified specifications, named movements and real photography — the same commitment to accuracy that drives this study. We publish open-water-safety research because the people who wear a dive watch are exactly the people who need to respect what cold water can do.
This report and its underlying data are free to cite and republish with attribution and a link to www.futurewristtech.com. For the full dataset, an interview, or a custom cut of the numbers for your state, contact our press desk.