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Joanne Nova
A prize-winning science graduate in molecular biology.
Researchers followed 80 per cent of the US population for two decades and found that cold temperatures contributed to a whopping 800,000 deaths while hot temperatures were linked to only 2,000.
They were looking at monthly temperature data in 819 locations across the US. Then, they checked the cardiovascular death rates and found the burden of excess deaths is “quite substantial.”
During cold periods, our blood vessels contract to reduce heat loss, which is why our skin looks slightly bluer or whiter in colder weather. But even a small reduction in volume makes our blood pressure rise. So it is not surprising that colder months are linked to significantly higher death rates from heart attacks, strokes, and coronary artery disease compared to milder periods. As the population ages and kidney disease and diabetes get worse, the deaths will increase.
Nearly every dollar we pour into preventing heat deaths will end up killing more people than it saves. It’s time climate ministries put more accurate costings on any policy aiming to reduce global temperature. We want numbers, and during cold months, the people need cheap oil or gas to keep them warmer.
Look at the shape of the curve. Wow!.
The ideal temperature for homo sapiens, at least to avoid a cardiovascular death, is apparently 23°C (or 74°F) .
Cold weather linked to 40,000 extra heart deaths each year in the US.
ScienceDaily
The relationship followed a lopsided u-shaped curve: both extreme heat and extreme cold raised the risk of death, but the effect was much stronger on the cold side. Researchers estimate that cold temperatures contributed to about 40,000 additional cardiovascular deaths each year during the study period (about 6.3% of all cardiovascular deaths), totaling around 800,000 deaths over two decades. In comparison, hot temperatures were linked to roughly 2,000 extra deaths annually (about 0.33% of all cardiovascular deaths), or about 40,000 over the same time frame.
Planning for Climate and Public Health Risks
The findings suggest that communities should pay closer attention to the dangers of cold weather when preparing for climate-related health risks.
“We tend to focus on heat-related impacts of climate change, but climate change also includes extreme cold. We need to not only have heat-related mitigation measures, but also cold-related mitigation measures,” he said.
UPDATE: The study measures outdoor temperatures and not indoor ones and doesn’t account for any extremes, but other studies on indoor temperatures show a strong lopsided mortality curve too, so in a sense the outdoor temperature average is a proxy for a cooler indoor temperature – especially in poorer households.
One major confounder in this research is that Vitamin D3 levels and exposure to beneficial infrared from the Sun are also limited in winter. In some ways monthly temperature is a proxy for sun exposure and Vitamin D3 levels. Hence some of the cold associated deaths could be easily prevented by increasing D3 levels, though a substitute for the infrared is not so easily found unless people spend more time outdoors at midday in winter.
REFERENCE
Pedro Rafael Vieira de Oliveira Salerno, et al. (2026) Cardiovascular disease mortality attributable to monthly non-optimal temperature in the United States: a county-level analysis. American Journal of Preventive Cardiology, 2026; 101514 DOI: 10.1016/j.ajpc.2026.101514
This article was originally published by JoNova and republished by CFACT.
