60 Heat-Related Mortality Statistics on Global Burden, Trends and Risk

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Heat-related mortality is measured in several ways, from death certificates to excess-death estimates and temperature-attribution models. Across global, U.S. and European evidence, the scale and trend depend on the geography, period, population and definition used.

The following figures summarize the most important measured and modeled findings:

  • Approximately 489,000 heat-related deaths per year worldwide were estimated for 2000–2019.
  • Asia accounted for 45% of estimated global heat-related deaths during 2000–2019.
  • Europe accounted for 36% of estimated global heat-related deaths during 2000–2019.
  • Heat-related mortality among people older than 65 increased approximately 85% worldwide between 2000–2004 and 2017–2021.
  • More than 70,000 people died in Europe during the June–August 2003 heatwave, according to a WHO summary.
  • An estimated 56,000 excess deaths occurred in the Russian Federation during a 44-day heatwave in 2010.
  • The United States recorded 1,600 deaths involving excessive heat in 2021, using death-certificate underlying or contributing cause codes.
  • The U.S. age-adjusted rate was 0.4 deaths per 100,000 population in 2021.
  • Arizona recorded 426 heat-related deaths in 2021, the highest count among the states listed in the CDC QuickStats release.
  • Europe had an estimated 61,672 heat-related deaths from 30 May to 4 September 2022 across 35 countries.
  • The 2022 European estimate had a 95% confidence interval of 37,643–86,807 deaths.
  • Italy had an estimated 18,010 heat-related deaths during the 2022 European summer study period.
  • The 2023 European estimate was 47,690 heat-related deaths across 35 countries.
  • Greece had the highest 2023 European study rate at 393 deaths per million people.
  • The 2023 European mortality burden was estimated to be 80% higher without societal adaptation since 2000.
  • The burden for people aged 80 and older was estimated to be 100.7% higher without present-century adaptation.
  • The United States recorded 43 fatal occupational injuries specifically due to environmental heat in 2022.
  • EPA counted more than 14,000 U.S. deaths with heat classified as a heat-related cause from 1979 through 2022.

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The World Health Organization summarizes studies estimating approximately 489,000 heat-related deaths per year worldwide during 2000–2019. This is a study-based estimate, not a direct worldwide count from death certificates, and it should not be combined arithmetically with the U.S. or European series.

According to WHO’s Heat and health, the geographic distribution of that estimated burden was:

Geography Share of estimated global deaths Period and measure
Asia 45% 2000–2019, WHO-cited estimate
Europe 36% 2000–2019, WHO-cited estimate

WHO also reports that heat-related mortality among people older than 65 increased approximately 85% between 2000–2004 and 2017–2021. This is a WHO indicator synthesis for an older population, rather than an all-age death count.

Historical heatwaves show how acute events can produce large mortality estimates. WHO summarizes more than 70,000 deaths in Europe during June–August 2003 and an estimated 56,000 excess deaths during a 44-day heatwave in the Russian Federation in 2010.

Exposure has also expanded: the number of people exposed to heatwaves increased by around 125 million between 2000 and 2016 worldwide. That is an exposure statistic, not a mortality estimate, so it provides risk context rather than an additional death total.

The CDC’s National Vital Statistics System recorded 1,600 U.S. deaths involving exposure to excessive heat in 2021, using underlying or contributing cause codes. The national age-adjusted rate was 0.4 deaths per 100,000 population.

The CDC reports these state counts for 2021:

State Heat-related deaths Age-adjusted rate where supplied
Arizona 426 5.2 per 100,000
Washington 171 Not supplied
Nevada 166 4.6 per 100,000
California 143 Not supplied
Oregon 133 Not supplied
Texas 93 Not supplied

The nine states with at least 20 deaths accounted for 1,226 of the 1,600 U.S. deaths in the defined 2021 series. These are observed death-certificate counts, so they are not directly interchangeable with modeled excess-mortality estimates.

The source for the national and state figures is the CDC QuickStats: Age-Adjusted Rates of Death Involving Exposure to Excessive Heat Among States with the Highest Numbers of Deaths — National Vital Statistics System, United States, 2021. The underlying or contributing cause definition can miss deaths where heat worsened another condition without being recorded in the relevant codes.

European studies provide modeled estimates based on temperature and mortality records rather than direct counts of certificates labeled heat-related. The 2022 study estimated 61,672 heat-related deaths between 30 May and 4 September 2022 across 35 European countries, with a 95% confidence interval of 37,643–86,807 deaths.

Selected 2022 country estimates were:

Country Estimated deaths Estimated rate
Italy 18,010 295 per million
Spain 11,324 237 per million
Germany 8,173 Not supplied
Greece Not supplied 280 per million
Portugal Not supplied 211 per million

The country estimates and rates come from the peer-reviewed Heat-related mortality in Europe during the summer of 2022. Its model estimated 18,547 additional summer heat-related deaths across the studied population for each 1°C increase in temperature, or 35.3 additional deaths per million people for each 1°C increase; these are model-derived slopes, not causal counts for every future degree.

For 2023, the peer-reviewed Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health estimated 47,690 heat-related deaths across 35 European countries, with a 95% confidence interval of 28,853–66,525 deaths. The analysis covered 823 contiguous regions representing approximately 543 million people.

The 2023 country rates were 393 deaths per million in Greece, 229 in Bulgaria, 209 in Italy, 175 in Spain and 136 in Portugal. These are epidemiological model rates for 2023, not official death-certificate totals.

Heat Mortality by Age, Sex and Vulnerability

Age is central to interpreting heat mortality. WHO identifies people older than 65 as a particularly important population for heat-mortality monitoring, while the European 2023 study modeled an especially large counterfactual effect for people aged 80 and older.

Without societal adaptation since 2000, the 2023 European heat-mortality burden was estimated to have been 80% higher. For people aged 80 and older, the modeled burden was 100.7% higher without present-century adaptation.

The 2022 European mortality analysis used 45,184,044 death records from January 2015 through November 2022 across 823 regions in 35 countries. Within that dataset, 22,000,519 records were for women and 21,913,050 were for men; these are dataset-composition figures, not heat-attributed mortality counts.

The same 2022 study represented more than 543 million people across its 35-country region set. The distinction matters: age, sex and population coverage describe who was included in the underlying records, while the heat-related totals are model outputs derived from temperature and mortality relationships.

The U.S. Bureau of Labor Statistics counted 43 fatal occupational injuries specifically due to environmental heat in 2022, compared with 36 in 2021. The BLS Census of Fatal Occupational Injuries covers fatal work injuries, so illness-related deaths not precipitated by an injury event are outside its scope.

BLS also reported 51 fatalities due to temperature extremes in 2022, up from 43 in 2021, an 18.6% increase. That broader category includes more than environmental heat alone.

For context, the BLS recorded 5,486 fatal work injuries in 2022, with an overall fatal work-injury rate of 3.7 per 100,000 full-time-equivalent workers. Construction and extraction occupations had 1,056 fatal work injuries, and their rate increased from 12.3 per 100,000 FTE workers in 2021 to 13.0 in 2022.

Farming, fishing and forestry had the highest occupational fatality rate at 23.5 per 100,000 FTE workers in 2022. These occupation-group figures cover all fatal work injuries, not only heat-specific deaths.

The figures are from the BLS Census of Fatal Occupational Injuries News Release: National Census of Fatal Occupational Injuries in 2022.

EPA’s U.S. indicator counted more than 14,000 Americans whose death certificates classified heat as a heat-related cause from 1979 through 2022 across the 50 states and District of Columbia. The EPA Climate Change Indicators: Heat-Related Deaths series reports that the rate of deaths directly resulting from heat generally ranged from 0.5 to 2 deaths per million people during that period, with substantial year-to-year variability and spikes.

The Chicago heatwave illustrates why attribution method changes the result. From 11–27 July 1995, Cook County death certificates recorded 465 heat-related deaths, while studies comparing total deaths with the long-term daily average estimated about 700 excess deaths in the Chicago area.

EPA also cites statistical approaches estimating more than 1,300 U.S. deaths per year from extreme heat, compared with about 600 per year in an underlying-and-contributing death-certificate dataset. Those values are not directly interchangeable: modeled attribution captures a broader relationship, while coded records use a narrower classification.

Adaptation can affect observed outcomes. EPA reports that heat-related deaths in Milwaukee during a 1999 heatwave were roughly half of what would have been expected after the city developed a response plan following 1995; this is an illustrative before-and-after comparison, not a randomized intervention estimate.

The central measurement limitation is therefore definitional. Death-certificate coding, excess-mortality analysis and epidemiological temperature-attribution models answer related but different questions, and the resulting figures should be compared only when their periods, populations, geographies and methods align.

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