Heatstroke is a severe, measurable subset of heat-related illness, but many widely cited datasets combine it with heat exhaustion or broader heat-attributable mortality. The figures below therefore identify the diagnosis, population, geography, period and denominator for each measure.
Key Heatstroke Statistics
These highlights span emergency care, seasonality, occupational exposure, mortality and sport:
- In the United States during 2006–2010, 326,497 acute heat-illness emergency-department cases were estimated.
- During 2006–2010, 5.4% of U.S. acute heat-illness emergency-department cases were diagnosed as heatstroke.
- In the United States during 2006–2010, the heatstroke emergency-department case-fatality rate was 99.4 deaths per 10,000 visits.
- During 2009–2010, U.S. heatstroke emergency departments recorded an estimated 8,251 annual visits.
- In the United States during 2009–2010, 54.6% of heatstroke emergency visits required hospitalization.
- In May–September 2023, the U.S. warm-season heat-related-illness emergency visit rate was 180 per 100,000 people.
- In May–September 2023, U.S. males had a heat-related-illness emergency visit rate of 271 per 100,000, compared with 104 among females.
- In May–September 2023, July and August averaged 303 U.S. heat-related-illness emergency visits per 100,000 people.
- In May–September 2023, HHS region 9 had a heat-related-illness emergency visit rate of 298 per 100,000.
- In 2025, U.S. active-component service members recorded 518 heatstroke cases, or 39.4 per 100,000 person-years.
- In 2025, recruit trainees had a U.S. military heatstroke rate of 127.1 per 100,000 person-years.
- In 2025, combat-specific military occupations had a heatstroke rate of 115.8 per 100,000 person-years.
- For 2000–2019, WHO estimated approximately 489,000 heat-related deaths per year worldwide.
- Between 2000–2004 and 2017–2021, heat-related mortality among people older than 65 increased approximately 85% worldwide.
- In summer 2022, Europe experienced an estimated 61,672 heat-related excess deaths.
- In 2000–2022, Japan’s reported ICD-10 X30 heatstroke mortality rate was 5.81 per million people.
- At the 2015 World Athletics Championships, self-reported heat-illness symptoms corresponded to 163.0 events per 10,000 athlete-exposures.
- At the 2016 Road Cycling World Championship in Qatar, reported exertional heat illness was 31.0 events per 10,000 athlete-exposures.
Contents
- Emergency-department burden and outcomes
- Age, sex and seasonal patterns
- Regional heat-related illness data and trends
- Military and occupational heatstroke statistics
- Mortality and the global heat burden
- Sports and exertional heatstroke data
Heatstroke Statistics: Emergency-Department Burden and Outcomes
A national analysis of U.S. emergency departments estimated 326,497 acute heat-illness cases during May–September 2006–2010. This Nationally Representative NEDS estimate covers all acute heat illness, not heatstroke alone, and the source was published as Summertime Acute Heat Illness in U.S. Emergency Departments from 2006 through 2010: Analysis of a Nationally Representative Sample (CDC Stacks).
Disposition among those acute heat-illness cases was substantial but not uniformly severe:
- 287,875 cases, or 88.2%, were treated and released.
- 38,392 cases, or 11.8%, resulted in hospital admission.
- 230 patients, or 0.07%, died in the emergency department; this excludes later inpatient mortality.
Heat exhaustion accounted for 74.7% of acute heat-illness ED cases, while heatstroke accounted for 5.4%. Among the coded heatstroke visits, the estimated ED case-fatality rate was 99.4 deaths per 10,000 heatstroke visits, with a 95% confidence interval of 78.7–120.1, and heatstroke was diagnosed in 77.0% of deaths among acute heat-illness ED cases.
A separate analysis of coded heatstroke visits estimated 8,251 annual U.S. ED visits during 2009–2010, equal to 1.34 visits per 100,000 population, with a 95% confidence interval of 1.23–1.45. The study reported that 54.6% required hospitalization and that the combined ED-or-hospital death proportion was 3.5% (Emergency Department Visits for Heat Stroke in the United States, 2009 and 2010).
These historical estimates use ICD-9-CM coding and survey-weighted ED data, so they should not be treated as current surveillance.
Heat-Related Illness Statistics by Age, Sex and Season
CDC’s analysis of May–September 2023 data from participating National Syndromic Surveillance Program facilities estimated a U.S. mean heat-related-illness ED visit rate of 180 per 100,000 population, with a 95% confidence interval of 155–208. HRI is broader than heatstroke, and the analysis is not population-based (Heat-Related Emergency Department Visits — United States, May–September 2023).
Age-specific mean HRI ED visit rates were:
| Age group | May–September 2023 rate | Measure |
|---|---|---|
| Younger than 18 | 95 per 100,000 | HRI ED visits |
| 18–25 | 211 per 100,000 | HRI ED visits |
| 26–54 | 222 per 100,000 | HRI ED visits |
| 55–64 | 207 per 100,000 | HRI ED visits |
| 65–74 | 173 per 100,000 | HRI ED visits |
| 75 and older | 120 per 100,000 | HRI ED visits |
The same 2023 analysis estimated a mean rate of 271 per 100,000 among males and 104 per 100,000 among females. These are participating-facility HRI estimates rather than heatstroke-specific population rates.
Seasonality was pronounced. July and August averaged 303 HRI ED visits per 100,000 during 2023, compared with 97 per 100,000 in May, June and September; across 2018–2022, the corresponding July–August average was 208 per 100,000 versus 112 per 100,000 in the other warm-season months.
Heatstroke Statistics Across U.S. Regions and Warm-Season Trends
Regional results from the 2023 CDC HRI analysis varied widely across HHS regions. The rates below are mean HRI ED visits per 100,000 during May–September 2023, not heatstroke-only rates.
| HHS region | Mean HRI ED rate | Period and measure |
|---|---|---|
| Region 1 | 69 | May–September 2023 HRI visits per 100,000 |
| Region 2 | 51 | May–September 2023 HRI visits per 100,000 |
| Region 3 | 121 | May–September 2023 HRI visits per 100,000 |
| Region 4 | 226 | May–September 2023 HRI visits per 100,000 |
| Region 5 | 102 | May–September 2023 HRI visits per 100,000 |
| Region 8 | 127 | May–September 2023 HRI visits per 100,000 |
| Region 9 | 298 | May–September 2023 HRI visits per 100,000 |
The model-based rate ratio for region 9 versus region 2 was 5.92, with a 95% confidence interval of 4.77–7.35. Region 4 versus region 2 had a rate ratio of 4.58, with a 95% confidence interval of 3.74–5.59.
In the 2006–2010 national acute heat-illness analysis, ED visit rates correlated with annual temperature anomalies at r=0.882, with p=0.005. This is an ecological correlation covering all acute heat illness; it does not establish causation.
Heatstroke Statistics in Military Populations and Occupations
The U.S. active-component military recorded 518 heatstroke cases in 2025, an incidence rate of 39.4 per 100,000 person-years. The Armed Forces Health Surveillance Division report, Heat Exhaustion and Heat Stroke Among U.S. Active Component Service Members, 2021–2025, uses one case per person per calendar year and describes a military surveillance population rather than civilians (report in PubMed Central).
Selected 2025 rates show how military subgroup exposure differed:
| Military subgroup | Heatstroke rate in 2025 |
|---|---|
| Male service members | 42.8 per 100,000 person-years |
| Female service members | 24.3 per 100,000 person-years |
| Recruit trainees | 127.1 per 100,000 person-years |
| Enlisted personnel | 36.8 per 100,000 person-years |
| Officers | 40.6 per 100,000 person-years |
| Combat-specific occupations | 115.8 per 100,000 person-years |
| Motor transport | 39.3 per 100,000 person-years |
| Pilot and air crew | 6.9 per 100,000 person-years |
| Repair and engineering | 7.9 per 100,000 person-years |
| Health care occupations | 23.9 per 100,000 person-years |
The occupation groupings are unadjusted surveillance rates. Combat-specific occupations include infantry, artillery, combat engineering and armor, while the pilot and air-crew estimate carries a small-subgroup caveat.
Heatstroke Mortality Statistics and the Global Heat Burden
Heat-related mortality is broader than medically coded heatstroke. WHO estimated approximately 489,000 heat-related deaths per year worldwide for 2000–2019; Asia accounted for 45% and Europe for 36% of the estimated total (WHO, Heat and health).
WHO also reported that heat-related mortality among people older than 65 increased approximately 85% between 2000–2004 and 2017–2021. For specific heatwave periods, estimated excess mortality included 61,672 deaths in Europe during summer 2022, about 70,000 deaths associated with the June–August 2003 European heatwave, and 56,000 excess deaths during a 44-day 2010 Russian Federation heatwave.
A 34-country study of ICD-10 X30 mortality during 2000–2022 reported these selected rates:
| Country | Reported heatstroke mortality rate |
|---|---|
| Japan | 5.81 per million population, 95% CI 4.43–7.62 |
| Cyprus | 2.51 per million population |
| China | 2.42 per million population |
These are reported ICD-10 X30 mortality rates, not all-cause heat-attributable mortality, and country comparisons are affected by reporting and coding differences (Emergency Department Visits for Heat Stroke in the United States, 2009 and 2010).
Heatstroke Statistics in Sports and Exertional Settings
Sports studies commonly use athlete-exposures, competitors or self-reported symptoms, so their denominators and case definitions are not interchangeable. A peer-reviewed review, Exertional heat stroke in sport and the military: epidemiology and mitigation, reported the following evidence (review in PubMed Central):
- At the 2015 World Athletics Championships, self-reported heat-illness symptoms corresponded to 163.0 events per 10,000 athlete-exposures; no medically confirmed exertional heatstroke cases were reported.
- At the 2016 Road Cycling World Championship in Qatar, reported exertional heat illness incidence was 31.0 per 10,000 athlete-exposures.
- Among the same cycling-championship athletes, self-reported history of exertional heatstroke corresponded to 1,159.4 per 10,000 athlete-exposures; this is not comparable with event-confirmed race-day incidence.
- Across three studies of recreational cyclists, exertional heat illness was reported at approximately 401.0 events per 10,000 competitors; the review synthesis covers all exertional heat illness, not heatstroke alone.
- In a 2016 cycling-championship study, 25% of participants exceeded a core temperature of 40°C and one reached 41.5°C; these physiological observations are not equivalent to diagnosed heatstroke.
For comparison with sport-specific exposure denominators, a military review reported overall exertional heatstroke incidence of 0.37 per 1,000 person-years, with 0.40 among men and 0.23 among women. The denominator differs from athlete-exposure studies, so the values should not be ranked directly against the sports estimates.