As the planet warms, heatwaves are becoming longer, stronger and deadlier – here are some of the worst
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With temperatures rising to almost 40C across Europe this week, ‘heatwave’ has certainly been the word on everyone’s mind. Against the backdrop of an ever-warming planet, these extreme weather events are becoming more common and even more intense.
Such scorching temperatures can be attributed to changes in circulation patterns – such as El Niño – which in turn change weather. As well as this, increased greenhouse gas emissions also contribute towards a warmer planet. Unsurprisingly, both factors are majorly impacted by human activities: from creating large-scale factories pumping out carbon dioxide, to the cars driven on roads emitting pollutants. In short, it’s impossible to talk about heatwaves without recognising humans’ role in causing them.
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As we brace ourselves for a summer likely filled with warmer temperatures, here we present some of the longest-ever heatwaves on record. Read on to discover when and where they occurred – and the devastating impacts they had.
France’s 2003 heatwave – 2 weeks
Following a relentless two-week-long heatwave in 2003 – with temperatures exceeding 40C – 15,000 heat-related deaths occurred in France. Most of these individuals were over the age of 75 and living alone.
With healthcare systems completely overwhelmed at the time, the nation has since revised its strategy to prevent a similar catastrophe. These policy changes include the implementation of a national heatwave plan, which features a warning system to categorise future heatwaves on a scale from green to red.
At the highest level, strict measures are enacted, ranging from school closures and altered working hours to the enforcement of reduced speed limits for vehicles, helping to mitigate heat-induced pollution.
Russia’s 2010 heatwave – 6 weeks
From late June to mid-August 2010, western Russia, including Moscow, experienced a brutal heatwave lasting approximately six weeks. Temperatures remained above 35°C for much of this time – exceptionally rare for the region – and even exceeded 38°C in Moscow.
In addition to intense heat, widespread wildfires worsened air quality, causing a dramatic spike in respiratory illnesses. The heatwave contributed to an estimated 55,000 deaths, making it one of the deadliest heatwaves in recorded history.
India and Pakistan’s 2015 heatwave – three weeks
In May and June 2015, a severe heatwave struck the Indian subcontinent, leading to more than 2,500 deaths in India and more than 1,100 in Pakistan. The southeastern Indian states of Andhra Pradesh and Telangana were particularly affected, with temperatures soaring above 47°C. The extreme heat overwhelmed healthcare systems and highlighted the vulnerability of outdoor workers and the elderly.
Phoenix’s 2023 heatwave – 31 days
In 2023, a major heatwave struck the city of Phoenix, Arizona. For 31 consecutive days – from 30 June to 30 July – temperatures exceeded 43.3C, leading to the heat-related deaths of 645 individuals. During the heatwave, one of Phoenix’s mitigation measures included the establishment of cooling centres. Essentially, these are safe, air-conditioned spaces where locals can gather to avoid the unrelenting heat outside.
Such scorching temperatures broke the record of the previous heatwave streak, set at 18 days back in 1974.
In light of the city’s ever-warming temperatures, an ordinance was passed back in 2024 which states employers must provide outdoor workers with access to rest, shade, water and air conditioning, as well as training to understand the signs of heat stress.
Japan’s 2018 heatwave – 3 weeks
Japan’s heatwave unfolded over three weeks in July 2018, peaking around 23 July when the country recorded its highest-ever temperature of 41.1°C in Kumagaya, northwest of Tokyo. It particularly affected densely populated urban areas with vulnerable elderly populations.
The Japanese government declared it a natural disaster. The heatwave caused over 1,000 deaths, with tens of thousands more hospitalised. Scientific attribution studies concluded that such a heatwave would have been virtually impossible without climate change.
UK summer of 1976 – 10 weeks
For many individuals, the summer of 1976 conjures memories of scorching hot temperatures in the UK. This 10-week-long heatwave occurred in multiple locations across England, with widespread spells of heat reported in southern and central regions. Some areas reported no rainfall for 45 consecutive days.
Cheltenham, in Gloucestershire, experienced the highest temperatures – exceeding 32C for a 7 day period.
In London, for the first time ever – thanks to the unrelenting heat – umpires were permitted to take off their jackets at the Wimbledon tennis championships. And in Derbyshire, prolonged high temperatures meant its Ladybower Reservoir ran entirely dry. Across the country, hosepipe bans were enforced and a Minister of Drought was even appointed.
Europe’s 2022 and 2023 heatwaves – 3 months
Across both 2022 and 2023, many nations – including France, Italy, Spain, Germany, the UK, Portugal and the Netherlands – were hit by heatwaves.
2022 marked the hottest-ever European summer, with wildfires and droughts also accompanying high temperatures. With such weather events also came an increase in heat-related deaths: estimates suggest around 61,000 individuals died between 30 May and 4 September of that year.
According to researchers, 56 per cent of the total heat-related mortalities may have been preventable in the absence of human-induced climate change.
When 2023’s summer rolled around, temperatures were just as scorching. That year, around 47,000 heat-related deaths were recorded as temperatures hit above average for 11 months. As well as this, 2023 marked the warmest September ever recorded, a marker of just how quickly our planet is warming.
Marble Bar’s 1923 heatwave – 6 months
For almost six months between 1923 and 1924, the town of Marble Bar in Western Australia faced a heatwave where temperatures reached – and sometimes exceeded – more than 37.8C, marking the longest-ever recorded heatwave anywhere on the planet.
A range of factors combined to cause the heatwave. Notably, Marble Bar’s location in the Pilbara region of north-western Australia puts it in prime location for minimal rainfall and an arid climate, helping to create favourable conditions for intense temperatures.
