There is no single temperature that automatically makes exercise unsafe because humidity, direct sunlight, and airflow often influence heat stress as much as the temperature itself.
Recent evidence confirms that, on average, older people tolerate heat less well, although there is an important nuance: age does not eliminate the ability to acclimatize to heat. In fact, recent studies show that older people can considerably improve their response through acclimatization.
The WHO indicates that heat-related mortality in people over 65 years of age increased by approximately 85% when comparing 2000–2004 with 2017–2021.
Heat is an environmental and workplace factor that can greatly affect health. Heat overload is a major cause of climate-related death and can exacerbate underlying conditions such as cardiovascular disease, diabetes, mental disorders, and asthma, among others, and increase the risk of accidents and certain infectious diseases. Heatstroke is a medical emergency associated with a high mortality rate.
The number of people exposed to extreme heat is increasing exponentially due to climate change in all regions of the world. Between 2000 and 2004 and again from 2017 to 2021, heat-related mortality among people over 65 years of age increased by approximately 85%.
Studies conducted between 2000 and 2019 found that 489,000 people die each year due to heat, with 45% and 36% of these deaths occurring in Asia and Europe, respectively (2). In Europe alone, 61,672 heat-related deaths were recorded in the summer of 2022 (3). Intense heat waves can lead to a sharp increase in mortality: in 2003, 70,000 people died in Europe as a result of the heat experienced between June and August. Another example is the excess mortality recorded in the Russian Federation in 2010, where 56,000 people died during a 44-day heat wave. Vulnerability to heat depends on physiological factors, such as age and health status, and on factors that increase exposure, such as socioeconomic and employment status.
The health effects of heat can be largely predicted and prevented through targeted, multi-sectoral public health policies and interventions. The WHO has published guidance to help public health institutions identify and respond to the risks of extreme heat. Climate change action and comprehensive risk management and preparedness can save lives now and in the future.
With aging, the physiological reserve for dissipating heat decreases, but the capacity for acclimatization remains and can significantly improve heat tolerance.
This is especially interesting because the 2026 study demonstrates that even in people aged 60–78, acclimatization for just 7 days produced physiological improvements comparable to those observed in younger people. It compared adults aged 60–78 with younger people and found that 7 days of heat exposure increased sweating and improved temperature control in both groups. The authors conclude that age does not prevent physiological adaptation to heat.
And there is another study that found something even more striking: after seasonal acclimatization, older adults reduced their body heat storage more than younger adults, suggesting that heat adaptation may be particularly beneficial with age.
A systematic review on heat tolerance in older adults. This study analyzes 24 studies and finds less sweating, less cutaneous vasodilation, and less effective cardiovascular/autonomic responses, with greater accumulation of body heat.
https://pubmed.ncbi.nlm.nih.gov/42113959/ Prolonged heat exposure in older adults. This study of individuals aged 61–80 years analyzes which factors determine who develops greater heat stress during hot environments. The interindividual factors explored did not significantly contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. In contrast, cardiovascular responses were exacerbated in women and individuals with type 2 diabetes. These findings improve the understanding of how interindividual differences contribute to heat-induced physiological stress in older adults.
Here in the Great Lakes, North East region the heat is one thing, Humidity and Smoke from all the wildfires is horse of a different color. Our Western States wildfire smoke combining with the Canada Wildfires Smoke at times have ramped up difficulty adjusting to the weather. For heat, a soaked kerchief loosely tied around the neck can cool the blood as it evaporates. Running cold water over the wrists can cool one off too. Humidity we're probably stuck with air conditioning, if possible. The Smoke...stinks, in more than one way. The eyes, sinuses, lungs all get stirred up. Staying indoors helps somewhat, but if such is from local wildfires it can be a situation of the only way to get away from the smoke is find a way to get away from the area.
The suffering of families losing their homes and having to endure pollution and heat waves is terrible. As of August 9, 2026, the area affected by wildfires has reached 529,192 hectares.
This figure exceeds both the area recorded on the same date in 2025 (the worst year on record) and the long-term average of the last 20 years (2006-2025).
Since mid-July, wildfires have ravaged France, Spain, and Portugal, forcing more than 300,000 people to evacuate their homes.
Authorities in Madrid, the Spanish capital, have declared the fires to be the worst the region has suffered to date.
French President Emmanuel Macron, who visited the fire-ravaged area in the Gironde region, described the wildfire as "completely unprecedented" and "the worst since World War II."
Map of France, Spain, and Portugal showing wildfire activity as of July 30. Dark red dots mark active fires detected in the last 24 hours, and light pink dots mark fires recorded since July 23. Wildfires are scattered across the three countries, with notable hotspots near Bordeaux in southwestern France; west of Madrid in central Spain; and in northern Portugal, near Valpaços. Source: NASA Enterprises (data as of July 30, 03:51).
The fires have erupted amid a sweltering summer with heat waves across Europe. Both France and Spain are experiencing another sharp rise in temperatures, with highs forecast to reach 41-42°C in France.
According to the European Forest Fire Information System (EFFIS), wildfires in the regions surrounding Madrid have burned approximately 1,570 square kilometers (606 square miles) since July 1. This area is more than twice the size of the city itself.
Drought in Europe at the end of July 2026
At the end of July, the drought remained stable and critical in Western, Central, and parts of Eastern Europe, the Balkans, and Italy, and worsened in the United Kingdom and Ireland. Drought warnings were issued for the Iberian Peninsula.
During this period, Europe experienced above-average temperatures, with the end of a widespread and prolonged heat wave that affected the first two-thirds of July and the beginning of a new, intense heat wave, which moved from the western Mediterranean and Italy toward the northwestern Balkans and east-central Europe.
Recent evidence confirms that, on average, older people tolerate heat less well, although there is an important nuance: age does not eliminate the ability to acclimatize to heat. In fact, recent studies show that older people can considerably improve their response through acclimatization.
The WHO indicates that heat-related mortality in people over 65 years of age increased by approximately 85% when comparing 2000–2004 with 2017–2021.
Heat is an environmental and workplace factor that can greatly affect health. Heat overload is a major cause of climate-related death and can exacerbate underlying conditions such as cardiovascular disease, diabetes, mental disorders, and asthma, among others, and increase the risk of accidents and certain infectious diseases. Heatstroke is a medical emergency associated with a high mortality rate.
The number of people exposed to extreme heat is increasing exponentially due to climate change in all regions of the world. Between 2000 and 2004 and again from 2017 to 2021, heat-related mortality among people over 65 years of age increased by approximately 85%.
Studies conducted between 2000 and 2019 found that 489,000 people die each year due to heat, with 45% and 36% of these deaths occurring in Asia and Europe, respectively (2). In Europe alone, 61,672 heat-related deaths were recorded in the summer of 2022 (3). Intense heat waves can lead to a sharp increase in mortality: in 2003, 70,000 people died in Europe as a result of the heat experienced between June and August. Another example is the excess mortality recorded in the Russian Federation in 2010, where 56,000 people died during a 44-day heat wave. Vulnerability to heat depends on physiological factors, such as age and health status, and on factors that increase exposure, such as socioeconomic and employment status.
The health effects of heat can be largely predicted and prevented through targeted, multi-sectoral public health policies and interventions. The WHO has published guidance to help public health institutions identify and respond to the risks of extreme heat. Climate change action and comprehensive risk management and preparedness can save lives now and in the future.
https://www.who.int/es/news-room/fact-sheets/detail/climate-change-heat-and-health?utm_source=chatgpt.com (2026)
With aging, the physiological reserve for dissipating heat decreases, but the capacity for acclimatization remains and can significantly improve heat tolerance.
This is especially interesting because the 2026 study demonstrates that even in people aged 60–78, acclimatization for just 7 days produced physiological improvements comparable to those observed in younger people. It compared adults aged 60–78 with younger people and found that 7 days of heat exposure increased sweating and improved temperature control in both groups. The authors conclude that age does not prevent physiological adaptation to heat.
https://pubmed.ncbi.nlm.nih.gov/42113959/ (2026)
And there is another study that found something even more striking: after seasonal acclimatization, older adults reduced their body heat storage more than younger adults, suggesting that heat adaptation may be particularly beneficial with age.
https://pubmed.ncbi.nlm.nih.gov/32592411/ (2020)
A systematic review on heat tolerance in older adults. This study analyzes 24 studies and finds less sweating, less cutaneous vasodilation, and less effective cardiovascular/autonomic responses, with greater accumulation of body heat.
https://www.mdpi.com/2227-9032/13/21/2785 (2025)
https://pubmed.ncbi.nlm.nih.gov/42113959/ Prolonged heat exposure in older adults. This study of individuals aged 61–80 years analyzes which factors determine who develops greater heat stress during hot environments. The interindividual factors explored did not significantly contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. In contrast, cardiovascular responses were exacerbated in women and individuals with type 2 diabetes. These findings improve the understanding of how interindividual differences contribute to heat-induced physiological stress in older adults.
https://pubmed.ncbi.nlm.nih.gov/38830263/ (2024)
Here in the Great Lakes, North East region the heat is one thing, Humidity and Smoke from all the wildfires is horse of a different color. Our Western States wildfire smoke combining with the Canada Wildfires Smoke at times have ramped up difficulty adjusting to the weather. For heat, a soaked kerchief loosely tied around the neck can cool the blood as it evaporates. Running cold water over the wrists can cool one off too. Humidity we're probably stuck with air conditioning, if possible. The Smoke...stinks, in more than one way. The eyes, sinuses, lungs all get stirred up. Staying indoors helps somewhat, but if such is from local wildfires it can be a situation of the only way to get away from the smoke is find a way to get away from the area.
The suffering of families losing their homes and having to endure pollution and heat waves is terrible. As of August 9, 2026, the area affected by wildfires has reached 529,192 hectares.
This figure exceeds both the area recorded on the same date in 2025 (the worst year on record) and the long-term average of the last 20 years (2006-2025).
Since mid-July, wildfires have ravaged France, Spain, and Portugal, forcing more than 300,000 people to evacuate their homes.
Authorities in Madrid, the Spanish capital, have declared the fires to be the worst the region has suffered to date.
French President Emmanuel Macron, who visited the fire-ravaged area in the Gironde region, described the wildfire as "completely unprecedented" and "the worst since World War II."
Map of France, Spain, and Portugal showing wildfire activity as of July 30. Dark red dots mark active fires detected in the last 24 hours, and light pink dots mark fires recorded since July 23. Wildfires are scattered across the three countries, with notable hotspots near Bordeaux in southwestern France; west of Madrid in central Spain; and in northern Portugal, near Valpaços. Source: NASA Enterprises (data as of July 30, 03:51).
The fires have erupted amid a sweltering summer with heat waves across Europe. Both France and Spain are experiencing another sharp rise in temperatures, with highs forecast to reach 41-42°C in France.
According to the European Forest Fire Information System (EFFIS), wildfires in the regions surrounding Madrid have burned approximately 1,570 square kilometers (606 square miles) since July 1. This area is more than twice the size of the city itself.
Drought in Europe at the end of July 2026
At the end of July, the drought remained stable and critical in Western, Central, and parts of Eastern Europe, the Balkans, and Italy, and worsened in the United Kingdom and Ireland. Drought warnings were issued for the Iberian Peninsula.
During this period, Europe experienced above-average temperatures, with the end of a widespread and prolonged heat wave that affected the first two-thirds of July and the beginning of a new, intense heat wave, which moved from the western Mediterranean and Italy toward the northwestern Balkans and east-central Europe.
https://joint-research-centre.ec.europa.eu/projects-and-activities/natural-and-man-made-hazards/forest-fires/current-wildfire-situation-europe_en
https://www.bbc.com/news/articles/cj638jx0l53o
https://joint-research-centre.ec.europa.eu/european-and-global-drought-observatories/current-drought-situation-europe_en