- Recycling Aluminum and Steel to Conserve Energy and Resources - September 2, 2025
- Monsoon Rains in South Asia and Their Role in Agriculture and Culture - August 30, 2025
- Glaciers in the Andes Supplying Water to Millions in South America - August 28, 2025
Breaking Temperature Barriers Across the Nation
The UK witnessed its most extraordinary heat on record when temperatures soared to a staggering 40.3°C at Coningsby in Lincolnshire during July 2022. This marked the first time in documented history that Britain experienced temperatures above 40°C, shattering previous records by a considerable margin. The summer of 2022 lasted from June to August and became the UK’s hottest summer ever. The intensity of this heat was so extreme that the Met Office issued its first-ever red extreme heat weather warning for parts of England on 15 July 2022, increasing the Heatwave Alert to Level 4, meaning there was a threat of illness and death among fit and healthy people. This unprecedented temperature formed part of Europe’s warmest summer on record, with significant impacts including wildfires, disruptions to transport and power systems, and increased mortality.
Recent Years Paint an Alarming Picture
2023 was provisionally the second warmest year on record for the UK, with Wales and Northern Ireland having their respective warmest years in a series from 1884. The warming trend has continued relentlessly into recent years, with 2024 ranking as the UK’s fourth warmest year with an annual average temperature of 9.78°C. The year’s peak came in August when the highest temperature of 34.8°C was measured in Cambridge on August 12th during a short but intense heatwave. Even more concerning, June 2023 was particularly warm compared to average, being the hottest June on record for the UK by a wide margin, and the joint-hottest September as temperatures peaked at 33.5°C on 10 September. June 2025 followed suit, becoming the warmest June ever recorded in England, and the second warmest for the UK in records since 1884.
The Scale of Human Impact
The devastating consequences of extreme heat in the UK have become increasingly apparent through mortality statistics. In 2022, England recorded the highest number of heat-related deaths ever, with more than 4,500 people dying due to high temperatures. The tragedy continued in subsequent years, as during the summer of 2024, there were over 1,000 deaths due to severe heat, mostly among elderly people aged 85 and over. Research reveals that one in five people in the UK has faced health problems caused by extreme heat over the past five years. The vulnerability increases significantly when temperatures rise, with the risk to life increasing in the UK when temperatures rise above 22°C. The UKHSA reported close to 3000 heat-related excess deaths in England over summer 2022, and during 4 days around the peak of the heatwave, 17–20 July, there were over 1000 excess deaths in the most vulnerable age group (65+ years).
When Normal Weather Patterns Break Down
The Met Office defines a heatwave as an extended period of hot weather relative to the expected conditions of the area, which may be accompanied by high humidity. In the UK, a heatwave is declared when the daily temperature meets or exceeds the heatwave temperature threshold for at least three days, with four different thresholds reflecting climate differences – the lowest covering places like Wales and Scotland at 25°C, and the highest covering London and parts of the East Midlands at 28°C. So far in 2025, there have been 11 days where temperatures have reached 30°C or higher, which based on station observations from 1931, has only happened twice before up to this point in the summer – in 1976 and 2018. The frequency of such extreme conditions highlights how dramatically weather patterns are shifting from historical norms.
Multiple Heatwaves Strike in Single Years
There have been several heatwaves across much of the UK in 2025, with several health alerts issued, including an amber alert in June, and records broken for the amount of the UK burnt by wildfires. Summer 2025 has seen the third official heatwave of the season by mid-July, with temperatures set to rise again. The pattern of back-to-back extreme heat events has become increasingly common, with the UK Health Security Agency issuing an amber heat health alert on 19 June 2025, with the Met Office predicting the first heatwave of 2025, and on 29 June, reporting that the south east of England was experiencing a heatwave with temperatures forecast to reach as high as 35C, with some locations forecast to remain above 20C overnight, known as a ‘tropical night’.
Historical Context Shows Unprecedented Change
Record-breaking temperatures are becoming increasingly common across the country, despite the UK being well known for cold, wet weather. The well-known hot summer of 1976 had more than a fortnight above 28°C, which is a key heatwave threshold in southeast England, but studies find that in today’s climate such conditions could persist for a month or more. The five warmest years in the UK series from 1884 include 2022, 2023, and 2020, and the ten warmest years have all occurred since 2003. This clustering of extreme years in recent decades represents a fundamental shift from the climate patterns that defined Britain for centuries. The newly released State of the UK Climate Report 2024 shows the UK is warming at a rate of approximately 0.25°C per decade, with 2023, 2022 and 2018 among the UK’s top-ten warmest summers in records back to 1884.
Marine Heatwaves Amplify Land Temperatures
Daily sea surface temperatures for the North-West Shelf show temperature profiles with arrows highlighting Marine Heatwaves in UK waters in June 2023 and May 2024. These events were particularly extreme due to their onset in the spring/early summer and significant (1-2 degree) increase compared to previous extremes falling at the same time of year. The marine heatwave in June 2023 contributed around 0.6°C warming over the UK compared to more average ocean temperature conditions, while the June UK monthly temperature record was broken by 0.9°C. A long-lasting marine heat wave hit the waters surrounding the United Kingdom and Ireland in spring 2025, with sea surface temperatures in some areas reaching up to 4 degrees Celsius warmer than normal by mid-May. The heat wave began in early March and continued into May, making it one of the region’s longest on record for this time of year. Over the past 40 years sea temperatures in the UK have risen by around 1°C, and overall the number of marine heatwaves has increased by around four per year in recent decades. In June 2023, the seas around the UK experienced a marine heatwave, with sea surface temperatures reaching their highest levels for June since records began in 1850.
Future Projections Paint a Hotter Picture
Met Office scientists have published a new study detailing the increasing likelihood of extreme temperatures in the UK, revealing that the chance of exceeding 40°C in the UK is accelerating at pace. The study, published in Weather journal, underscores the need for people and organisations to prepare for even higher heat extremes in the near future. Recent projections indicate that by the end of the century, 93% of the year will experience marine heatwave conditions, based on the 2000-19 climatology. An attribution study by the Met Office found that the likelihood of beating the UK land June temperature record had at least doubled compared to when it was first set in 1940, with around a 3% chance of beating the record in a 1991-2020 climate and, by the 2050s, a record could be occurring around every other year on average under a high-emissions scenario. Met Office climate predictions suggest that all areas of the UK will be warmer by the end of the 21st century, with hotter and drier summers also becoming more common.
Global Context Reinforces UK Trends
The World Meteorological Organization has confirmed a sobering milestone: the year 2024 was the warmest on record, with global average temperatures 1.55°C above pre-industrial levels. This likely marks the first full calendar year to breach the 1.5°C threshold set by the Paris Agreement. The World Meteorological Organization has confirmed that 2023 is the warmest year on record, by a huge margin, with exceptionally high sea surface temperatures around the globe. According to the report, 2023 annual average global temperature was 1.45°C above pre-industrial levels (1850–1900), which is 0.16°C higher than the previous record in 2016, approaching the Paris Agreement limit of 1.5°C. An analysis from Climate Central shows that the fingerprints of climate change were all over 2023’s unusually hot summer globally. Over 6.5 billion people – 81% of the global population – experienced at least one hot day in July 2023 that was at least three times more likely because of climate change. Of those, at least 2 billion people saw climate-induced high temperatures on every single July 2023 day.
The Rarity Factor
Current UK heatwaves represent events that would have been virtually impossible under natural climate conditions. The 2023 UK annual mean temperature would have been around a 1-in-500 year event in a climate unaffected by humans, but by the end of the century, under a medium emissions scenario, it could occur almost every year (79% each year). According to World Weather Attribution, without human induced climate change these heat events would have been extremely rare, with maximum heat like in July 2023 virtually impossible to occur in the US/Mexico region and Southern Europe if humans had not warmed the planet by burning fossil fuels. Met Office Senior Scientist Mike Kendon noted that while our climate will remain variable, with periods of cold and wet weather, what we have observed over recent decades is a number of high temperature records tumbling. We expect this pattern to continue as our climate continues to change in the coming years as a result of human-induced climate change.
The Verdict on Climate Change
The scientific consensus is unambiguous regarding climate change’s role in UK heatwaves. Human-induced climate change has made the UK’s 2023 mean temperature significantly more likely compared to a pre-industrial climate. UK mean temperatures have been shifting over the decades as a result of human-induced climate change. The trend in UK climate observations is consistent with that observed globally. Attribution of the record-shattering global annual heat in 2023 to human and natural factors is fundamentally required for reliable predictions of upcoming global warming and its impacts. An observation-model comparison of global hot areas supports a key role for human-induced climate change, with a small contribution from El Niño. Heatwaves are extreme weather events and because of climate change, they are becoming longer and more intense. The overwhelming body of evidence points not just to climate change as a contributor, but as the primary driver transforming what were once-in-a-lifetime events into regular occurrences that Britain must now learn to live with.
