This week’s heatwave is the hottest ever recorded in Europe, as well as the most humid, and it is likely to cause thousands of deaths.

Although a potential “super El Niño” is forming in the Pacific Ocean, this didn’t play a role in the heatwave, a study by the World Weather Attribution network of scientists has found. Instead, global warming is clearly to blame.

The study analysed how likely the average daily maximum temperature projected for 26 to 28 June in western and central Europe would have been in the cooler climates of 1976 and of 2003.

While the weather pattern – a low-pressure heat dome that is trapping hot air from the south – isn’t unusual, the temperatures are. Fifty years ago, a typical June heatwave would have been about 3.5°C cooler, and the temperatures seen over the next three days would have been a less-than-one-in-10,000-year occurrence.

Daytime temperatures have 44°C  (111°F) in one French town, and nighttime temperatures have remained above 30°C (86°F) in parts of Spain.

“This event would not have been possible in June without climate change,” at Imperial College London said at a media briefing on 25 June. “The three-day nighttime temperatures would not have been possible at any time of year without climate change.”

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The humidity has also been unprecedented, reaching more than 50 per cent in many British cities. Dew-point temperatures have been in the low 20s, as compared to the single digits during the July 2022 heatwave that set the UK’s temperature record.

The wet-bulb globe temperature, which measures not just air temperature but also humidity, heat radiation and air movement, has broken or is expected to break records in almost half of European cities, the study found.

Humidity amplifies health risks because it slows evaporation, making sweating less effective. While older people or those who have a chronic illness are in particular danger, so are migrants and people experiencing homelessness.

“What we see very clearly… is how unequal the effects of this heatwave are and how that really demonstrates the inequality that widens due to climate change,” said , also at Imperial College London. “Because it’s of course people who are particularly vulnerable who are most likely to lose their lives.”

While it is too soon to look at excess mortality, a previous study found a smaller heatwave in June and July 2025 killed 2300 people in London and 11 other European cities.

“The health impacts of this heatwave are likely to be extremely high across large parts of northern and central Europe,” said Keeping.

Heatwaves will become even more intense and frequent unless we rapidly cut fossil fuel emissions, the researchers stressed. And Europe, the fastest warming continent, is not ready, as it has an ageing, urban population living in cities built for a cooler era. In the UK, only 5 per cent of homes have air conditioning.

Besides AC, Europe should invest in passive cooling like building insulation, ventilation, green roofs and walls and trees along streets, they said. It should also expand its heat response to include oft-forgotten groups like people with mental health conditions and those who are pregnant, said Carolina Pereira Marghidan at the Red Cross Red Crescent Climate Centre.

“Europe has heat action plans, but research has also shown that sometimes they do not cover all the groups that may be vulnerable,” she said.

Resting body temperature rises a little bit each year in women from the age of 18 to 42, for reasons that are still being figured out. The finding opens up the possibility of using temperature-sensing wearables to track ageing and detect perimenopause or potential health problems.

“We think there is a lot of information about health in the temperature signal,” says  at SRI International, a research institute headquartered in California. “We hope this facilitates investigations to identify novel markers of conditions – it may be an untapped resource of information about our health.”

Gombert-Labedens and her colleagues analysed data from a  that asked more than 750 women aged 18 to 42 to measure their oral or rectal temperature with a thermometer every day when they first woke up.

The readings showed that, on average, body temperature was lower during the first half of the participants’ menstrual cycles and higher during the second half, after ovulation occurred. Many fertility-tracking apps use this temperature jump to predict a user’s fertile window.

Gombert-Labedens and her colleagues re-examined the data in more detail to investigate the effect of age on temperature across different stages of the menstrual cycle. They found that each year from age 18 to 42, the participants became a fraction warmer, on average. As a result, those aged 35 and older tracked about 0.05°C hotter than the younger subjects across both halves of the menstrual cycle.

This is consistent with the team’s previous research that found that finger skin temperature, measured continuously by a smart ring, was  than in those aged 18 to 35.

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Further research is required to explain why this temperature increase occurs, but it probably has something to do with hormonal changes, especially towards the end of the reproductive years, says Gombert-Labedens. When perimenopause begins, temperature can increase suddenly and cause hot flushes and night sweats, but it’s unclear whether this is linked to the same mechanisms, she says.

The study only included women who did not use hormonal contraception and did not have hormonal conditions such as PMOS (polyendocrine metabolic ovarian syndrome, previously known as PCOS), so we don’t yet know how these factors might affect body temperature over time.

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Other research has found that after menopause, body temperature in women tends to  and become similar to that of men.

The higher temperature around midlife may explain why anecdotally, some women at this age say they don’t feel the cold as much as they used to, says Gombert-Labedens. “We speculate that the higher temperature in midlife women could influence their perception and reaction to environmental temperature,” she says.

As smart rings and other temperature-sensing wearables become more popular, it may be possible to identify patterns or deviations in individuals’ temperature trends that signal the approach of menopause, provide an estimate of their rate of biological ageing or detect early signs of ovarian cancer or other conidtions, says Gombert-Labedens.

The special fur that numbats evolved to conserve energy is now putting them at risk of overheating amid Australia’s increasingly hot temperatures.

Numbats (Myrmecobius fasciatus), which are unusual marsupials in that they are active during the day, eat termites hidden under wooden logs and topsoil. Since these insects are a low-calorie meal, numbats – which typically weigh around 500 grams – have evolved fur that absorbs heat from the sun, saving calories that would otherwise go towards generating body heat.

As temperatures rise, that evolutionary trait may be backfiring, with numbats overheating within minutes of feeding under direct sunlight, says at Curtin University in Perth, Australia.

Numbats used to roam across southern Australia, but over the past two centuries, they have fallen prey to the cats and foxes brought over by European colonisers. Today, these endangered animals are concentrated in just two small nature reserves in Western Australia.

In an effort to raise numbers, conservation groups have been gradually relocating the marsupials into predator-protected areas of their native territory. Global warming, however, has made some of these areas much hotter and drier.

“The unprecedented rates of environmental change now occurring due to human-induced global warming mean that it is critical that we understand the ecological consequences of changes in environmental conditions if we are to predict future patterns of species distribution and abundance, and conserve and manage them,” Cooper and her colleague at the University of Western Australia write in their paper.

To learn more, the pair used a thermographic camera to film 50 of the wild animals as they fed on termites at different times of the day throughout 2020 and 2021.

At each site, they used a portable weather station to record factors such as air temperature, wind speed and humidity. They then plugged this data into a computer programme that models how environmental conditions affect numbats’ internal temperatures.

The pair found that on days of high heat stress – for example, a dry environment with 40°C air temperature – numbats overheat within 10 minutes of being in direct sunlight. They then need to stop feeding and hide from the sun until their body temperature drops.

Shade helps, but is often sparse, so seeking it limits numbats’ termite-hunting turf, says Cooper. The model also suggests that high outdoor temperatures combined with radiating ground heat could cause numbats to overheat even in the shade.

Night feeding isn’t an option for numbats, which have poor night vision and lack the strength to break into the mounds where termites hide at night.

To help overcome these problems, Cooper recommends conservation groups relocate numbats to relatively cooler areas within their territory and ensure there is sufficient shade.