22 June 2026
The Met Office has issued a rare red warning for extreme heat, which indicates there is a risk to life. This will cover parts of central and southern England and Wales on Wednesday and Thursday.
Temperatures in Reading could reach 40°C on Wednesday, 24 June, according to Met Office forecasts - a peak that would break University records.
The temperature record for June currently sits at 34.0°C degrees, as recorded on 26 June 1976. The highest temperature ever recorded at the Reading University Atmospheric Observatory was 37.6°C, on 19 July 2022.
Heathrow Airport is almost 7 degrees hotter than normal for this time of year - find out more via istheukhotrightnow.com/
For interviews, contact the University of Reading Press Office on 0118 378 5757 or pressoffice@reading.ac.uk
Commenting, Dr Jess Neumann, University of Reading, said: "The UK Met Office has issued a rare extreme heat red warning, which means there is a danger to life.
"This heat is going beyond your regular "summer holiday, beach days and ice creams" and must not be underestimated.
"The impacts of heatwaves on people are wide-ranging – some are direct and potentially very severe such as heat exhaustion, heatstroke or death. However, the effects of heat are not always so obvious or immediate - dehydration, lethargy, headaches, or trapped air pollutants can affect us all.
“People with respiratory, cardiovascular or other underlying health conditions, babies, children, people working outside and other vulnerable groups are particularly at risk. None of us are immune to extreme heat and we must look after ourselves to stay safe and well.
“Staying cool is essential. Drink plenty of fluids, stay out of the direct sun, seek shade and cooler areas, avoid exercising, apply suncream if in the sun and wear appropriate clothing. Don’t wait until you are thirsty – drink plenty and regularly.
“There’s a chance of some tropical nights in the coming days. This is where nighttime temperatures stay above 20 degrees Celsius. Our houses are designed to insulate, and many of us don’t have air conditioning, making it harder for our bodies to cool down at night.
"If you have a fan, now is the time to get it out. Place a bowl of ice in front of a fan. Wet flannels and wet towels, cool showers, removing duvets and wearing loose cloths can help with cooling the body.
“Effects of prolonged heat on the environment includes increased risk of wildfires, rapid water evaporation leading to falling river and reservoir levels and increased concentrations of pollutants in water sources. Wildlife including birds, mammals and insects will die if they cannot find access to freshwater so consider filling bird baths, or leaving shallow dishes of water for wildlife in your garden.”
Regius Professor Hannah Cloke, University of Reading, said: "The Met Office has issued a red weather warning, its highest level of alert, for parts of southern England and Wales from Wednesday morning through to Thursday evening. A red warning means the risk is to everyone, not just the vulnerable. That context matters when thinking about what the body is actually being asked to cope with.
"Wet bulb temperature is a measure that combines heat and humidity to give a truer picture of how the body experiences extreme weather. It reflects how well sweat can evaporate from the skin, because evaporation is what cools us down. When humidity is high, sweat cannot evaporate as effectively, so the body struggles to regulate its temperature even if the air temperature itself is not at its peak.
"The critical threshold is a wet bulb temperature of 35°C, the point at which even a healthy person at rest cannot cool themselves, regardless of how much water they drink or shade they find. We have never come close to that in the UK, but that does not mean wet bulb conditions cannot become genuinely dangerous well below it.
"What makes this week particularly notable is not just the heat but the humidity. During the 2022 heatwave, which set the UK's all-time temperature record, conditions in Reading on the peak day at 10am were very dry, around 28% humidity at 32 degrees. This week's forecast combines temperatures at 10am of around 30°C with humidity closer to 50%, which produces a considerably higher wet bulb reading. In practical terms, that means the body has to work harder to cope despite the air temperature being somewhat lower than in 2022.
"It is the combination of heat and humidity that matters, not the thermometer alone. Humid heat is harder heat."
Professor Richard Allan, University of Reading, said: “A heatwave in June is par for the course, but temperatures nudging toward 40°C were unprecedented for the UK up until 2022. Whilst May brought record dry heat, this week will see a more muggy heatwave that makes it difficult to stay cool and critical for those with underlying health conditions.
“It is blindingly obvious that heatwaves will increase in severity as rising greenhouse gases stifle the planet’s ability to lose heat to space. A warmer atmosphere’s greater thirst for water also means more rapidly onsetting drought, but also the intensification of extreme rainfall and associated flooding as excess water drained from the soil and oceans is channelled into storms that can often be sparked off by summer heat.
“The reality of global warming talked about when I was young in the 1980s is now playing out, yet the solution to avoid further dangerous climate change remains unchanged - upgrade our industry, transport and agriculture to vanquish greenhouse gas emissions across all sectors of society.”
Dr Akshay Deoras, University of Reading, said: "This is not just a heatwave, it is a heat-dome driven furnace that will grip most of southern UK and push temperatures into truly exceptional territory.
“We are looking at an intense and record-breaking spell of heat with widespread impacts on public health, infrastructure and essential services. Unlike the heatwaves of May 2026 and July 2022, elevated humidity levels are expected to make conditions feel even more oppressive and dangerous by severely reducing the body's ability to cool itself through sweating.
“Long-standing June temperature records are set to be shattered by 25 June, potentially by a significant margin, and with temperatures edging dangerously close to levels previously thought almost unimaginable in the UK.
“The driving force behind this event is a heat dome, which is a vast area of high pressure parked over the UK and western Europe. Think of it as a giant atmospheric lid, suppressing cloud formation and allowing relentless sunshine to bake the ground day after day. At the same time, air sinking beneath the high pressure compresses and warms, much like air heating up inside a bicycle pump when it is squeezed.
“Human-driven climate change has provided the springboard for this event, loading the atmosphere with extra heat and making extreme temperatures far more intense than they would have been in the past.
“Adding to the concern is the likelihood of widespread tropical nights, where temperatures remain above 20°C after dark. This prevents homes and buildings from cooling down, leaving many people struggling to sleep and reducing the body's ability to recover from the daytime heat.
“Hydration and staying out of direct sunlight are absolutely crucial. People should be aware of the early signs of heat-related illness, including headaches, dizziness, excessive tiredness, muscle cramps, nausea and confusion. It is essential to keep indoor spaces as cool as possible, and checking on vulnerable friends, relatives and neighbours can make a significant difference.
“There is also a hidden danger around water. Whilst many people will seek relief at beaches, lakes and rivers, cold water shock remains a serious risk. The contrast between very hot air temperatures and much cooler water can trigger an involuntary gasp response and breathing difficulties, so caution is essential.”
Professor Andrew Charlton-Perez, University of Reading, said: “The conditions this week provide a stark warning. The UK urgently needs to adapt to increases in the severity of extreme weather.
“There is a lot to do, not least in the education sector. I hope all nurseries, schools and colleges will be able to put in place climate action plans this week to protect learners and staff from the heat and prevent lost education.
“There are many organisations who can help schools with climate action plans, including the Climate Ambassadors programme. There are tough choices ahead, do we need increased cool spaces in our public buildings and how do we pay for and power them? What’s clear is these discussions can’t wait any longer.”
Extra resources:
Contact the University of Reading Press Office on 0118 378 5757 or pressoffice@reading.ac.uk
Visit istheukhotrightnow.com/ to see how extra warm the UK is.
Read: Glastonbury Tor shows stripes to start climate conversations - Show Your Stripes Day 2026
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