2026 Heatwaves: The Story So Far
From late spring and into the start of Summer, spells of very extreme hot weather impacted Europe, breaking many records. In May, the UK had its highest maximum and highest minimum temperatures broken for that month. The same thing happened again a month later during a separate heatwave. Before we dive deeper into the heatwaves themselves, there are a couple of definitions to understand first. A heatwave in the UK is defined as three consecutive days in which a threshold temperature is reached. This threshold changes geographically by county, ranging from 28°C in London, Cambridgeshire and surrounding counties, reducing by 1°C bands down to 25°C in the Southwest, Wales, the North, Scotland and Northern Ireland [1]. Another definition that is relevant to this period is a tropical night. This occurs when temperatures do not drop below 20°C overnight, making the impact of heatwaves on humans much more disruptive [2].
May
May started out as a relatively cool and unsettled month, with a lower-than-average mean temperature before the 19th. However, high pressure became established over the Netherlands and Germany, causing southerly winds and bringing the hot and sunny airmass from southern Europe. By the 23rd, 30°C was reached across London and the Southeast, and temperatures rose day by day before reaching their maximums on the 26th – 35.1°C at the Kew Royal Botanical Gardens. The previous maximum was 32.8°C back in May 1944 and during this heatwave more than 20 stations broke that record. On top of this, parts of the UK experienced tropical nights, with Kenley and Battersea minimum temperatures on the 26th being recorded at 21.3°C and 20.4°C respectively. On the 27th Camborne in Cornwall broke a record for the highest minimum temperature for the UK, with the temperature not dropping below 21.4°C. [3]. By Friday the 29th frontal systems from the Atlantic blew in and brought a cooler airmass over the UK, ending the heatwave.
Only a year before, a Met Office Climate Attribution Study published in the Royal Meteorological Society’s June 2025 issue of Weather [4] had highlighted that the chance of exceeding the May Maximum Temperature Record in the UK was now 3 times more likely in our current climate. With natural climate forcing, the probability of the event occurring is estimated to be 1-in-106 years, but in today’s climate with anthropogenic forcing, the probability of this event is estimated to be 1-in-33 years [4]. This year ended up being one of those 1-in-33.
During this heatwave, many properties suffered water service issues, and rail transport was severely disrupted due to track defects. Unfortunately, with the heatwave coinciding with the bank holiday/half-term break, 19 children and adults died due to drowning, highlighting the dangers of entering water bodies to cool off [5].
June
Just a month after the May temperatures broke monthly records across Western Europe, another heatwave began building on the 20th June. As high pressure remained over central Europe, it allowed very hot air from over northern Africa to gradually head north, warming further as it did so. By the 23rd of June, both France and Spain recorded their warmest June days on record, which were then broken again on the 24th, alongside a swathe of red heat alerts across both countries [6]. In the UK, the first day of the heatwave began in Writtle, Chelmsford on the 21st [7]. The Met Office issued red warnings for heat for the 24th and 25th, with amber alerts all week. The record for the hottest June day was broken on the 24th after 36.1°C was recorded at Gosport (beating the previously famous 1976 value of 35.6°C) [8]. This record was then broken again on the 25th, when Merryfield in Somerset, recorded 36.7°C. The heat then continued into Friday the 26th for the East of England, where for the third day in a row the hottest June day record was broken, with 37.7°C recorded at Lingwood in Norfolk. The Netherlands also broke their hottest June day record on the 26th, reaching 39.4°C. The heat then moved eastwards towards Central Europe, with Denmark, Austria, Hungary, Germany and Poland breaking records on the 27th and 28th. In Germany, the highest minimum temperature of 29.4°C also broke the previous record [6].
Impacts and the Changing Climate
Heatwaves such as these pose a very serious threat to human health, not only from accidents in water as mentioned above, but also with heat-related illness and death. This is primarily from high humidity, which controls how much of an effect evaporative cooling can have. When the air is 100% humid, water cannot evaporate and therefore cooling cannot occur [9]. The June 2026 heatwave had high humidity, meaning it felt very oppressive. To put it into context, even with humidity, during the 2022 heatwave that led to >40°C temperatures in the UK more than 60,000 people died across Europe from heat-related conditions. Combining this with the water shortages, melting roads, railways warping, energy surges due to air conditioning unit use and disruptions to sleep, there is an increase in medical emergency calls and massive strain is placed onto our infrastructure and services [10].
What must be reiterated is that without human-led climate change, temperatures felt from the July 2022 and both the May and June 2026 heatwaves would be virtually impossible. If the same heatwave setup was experienced back in the famous 1976, daytime temperatures would have been ~3.5°C cooler, and nighttime temperatures ~2.4°C cooler [10]. As climate change is severely ramping up the frequency and intensity of heatwaves we experience, it will only put more strain on humans, and services going forward. With that being said, there are many ways in which you can help yourself during these kinds of heatwaves [11]:
- Make sure you drink plenty of water.
- Keep to the shade as much as possible.
- Keep active activities to the beginning or end of the day.
- Close curtains and windows during the day and open them at night.
- Place a fan next to an open window to increase circulation at nighttime.
- If you do head out into bodies of water, make sure to check the water temperatures, bring a life jacket if suitable, and try to keep to areas manned by lifeguards.
We hope you all stay safe out there, and increase our resilience to such extreme weather going forward.
References
[1] Met Office (2026a). What is a heatwave? Available at: https://weather.metoffice.gov.uk/learn-about/weather/types-of-weather/temperature/heatwave (accessed: 02/07/2026)
[2] Met Office (2025a). Understanding tropical nights and their impact. Available at: https://www.metoffice.gov.uk/blog/2025/understand-tropical-nights-and-their-impact (accessed: 02/07/2026)
[3] Met Office (2026b). May 2026 Monthly Weather Report. Available at: https://www.metoffice.gov.uk/api/assets/file/mwr_2026_05_for_printpdf?prefix=assets&prefix=assets (accessed: 01/07/2026)
[4] Rebecca Holliday, Mark McCarthy, Jennifer Pirret and Emily Wallace (2025). Record-breaking May heat in the UK: contrasting the extreme temperatures of 2024 and 1944 using climate attribution. Available at: https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.7740 (accessed: 01/07/2026)
[5] Royal Life Saving Society (2026). The Royal Life Saving Society UK welcomes Prime Minister’s commitment to do “everything we can” to prevent drownings. Available at: https://www.rlss.org.uk/news/rlssuk-welcomes-prime-ministers-commitment-to-do-everything-we-can-to-prevent-drownings (accessed: 01/07/2026)
[6] World Meteorological Organization (2026). Record-breaking heat spreads through Europe. Available at: https://wmo.int/media/news/record-breaking-heat-spreads-through-europe (accessed: 01/07/2026)
[7] Ben Rich (2026). Four-day extreme heat warning begins as temperatures could hit 38C. Available at: https://www.bbc.co.uk/weather/articles/c932k0lewygo (accessed: 01/07/2026)
[8] Ella Kipling and Anna Lamche (2026). UK sees hottest June day on record as 31.6C recorded in Hampshire. Available at: https://www.bbc.co.uk/news/articles/c30y619glveo (accessed: 01/07/2026)
[9] Met Office (2025b). What is humidity and how does it affect human health? Available at: https://www.metoffice.gov.uk/blog/2025/humidity-and-how-it-affects-health (accessed: 02/07/2026)
[10] World Weather Attribution (2026). Fossil fuel emissions have rapidly worsened European heatwaves in just a few decades. Available at: https://www.worldweatherattribution.org/fossil-fuel-emissions-have-rapidly-worsened-european-heatwaves-in-just-a-few-decades/ (accessed: 02/07/2026)
[11] Met Office (2026c). Red Extreme Heat Warning in force as record-breaking June temperatures forecast. Available at: https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2026/red-extreme-heat-warning-in-force-as-record-breaking-june-temperatures-forecast- (accessed: 02/07/2026)
