Why this heatwave feels worse than the last one
Why this heatwave feels worse than – This week, England and Wales are bracing for a second heatwave of the year, with June temperature records under threat. While the high temperatures are reminiscent of May’s extreme conditions—reaching into the mid- to high 30s Celsius—many people report that the current wave feels more oppressive. The reason lies in a complex mix of environmental factors that amplify the perceived heat beyond what the thermometer alone suggests.
The Science Behind the Heatwave’s Intensity
A persistent heat dome, a large and static area of high pressure, is the primary driver of this intense heat. Dr. Akshay Deoras, a senior research scientist at the University of Reading, explained to BBC Weather that such weather patterns create a unique challenge. As air sinks through the atmosphere, it compresses and warms, while simultaneously drying out. This process prevents cloud formation, allowing unbroken sunshine to intensify ground temperatures. The result is a feedback loop where the air grows hotter, and the ground retains even more heat, creating a sensation of extreme discomfort.
Compared to the May heatwave, which centered over the UK, this week’s heat dome originated in the sub-tropical regions and has shifted further north and east. This change has led to a south-easterly airflow, carrying hotter and moister air into the country. The increased humidity plays a critical role in making the heat feel more severe. While the actual air temperature may register at 35°C, the combination of humidity and the stagnant heat dome can push the “feels like” temperature to as high as 41°C. This phenomenon, known as the heat index, measures how hot the air feels based on both temperature and moisture levels.
Tropical Nights and Their Impact
Overnight temperatures are also expected to remain stubbornly high, with some regions not dropping below 20°C. These “tropical nights” are a defining feature of the current heatwave. For instance, Thursday night could see the warmest June night on record, as minimum temperatures in Wales, the Midlands, and the South East are projected to stay between 21 and 23°C. In fact, certain areas may surpass the existing UK and England record of 22.7°C set in 1976, as well as Wales’ 20.3°C record, which was just established this week.
What makes these nights particularly challenging is that the “feels like” temperature may remain around 27°C even at the coolest moments of the night. This is a significant shift from previous heatwaves, such as the July 2022 event, where tropical nights occurred but were often isolated. In contrast, the current wave could lead to consecutive tropical nights, leaving the body without a chance to cool down between daytime spikes. This continuous exposure increases the risk of heat-related illnesses, even for individuals who are otherwise healthy.
Health Implications of Humidity
Humidity levels are a key factor in how the heatwave affects human health. During hot weather, our bodies regulate temperature through sweating. As sweat evaporates, it cools the skin and the surrounding air. However, in humid conditions, the evaporation process is slower, reducing the body’s ability to dissipate heat effectively. This can lead to a heightened sense of discomfort and greater strain on the cardiovascular system.
Dr. Deoras emphasized that the current heatwave is not just an isolated event but a “heat-dome driven furnace” that could set new benchmarks. He noted that while the July 2022 heatwave also reached 40°C, the air was notably drier. That contrast highlights how humidity alters the experience of heat, making the current conditions more dangerous. The prolonged exposure to high humidity could increase the likelihood of heat exhaustion, especially for vulnerable populations such as the elderly, young children, and those with pre-existing health conditions.
One of the most alarming aspects of this heatwave is the potential for multiple consecutive tropical nights. These warm, humid conditions not only disrupt sleep but also prevent the body from recovering during rest periods. As a result, the cumulative effect of heat and humidity can lead to a range of health issues, including dehydration, fatigue, and even heatstroke. The extended duration of these nights means that the body remains in a state of thermal stress for longer, compounding the risks associated with high daytime temperatures.
Mitigating the Effects of Extreme Heat
While the weather conditions are severe, there are steps individuals can take to reduce their risk. Staying indoors during the hottest parts of the day, using fans or air conditioning, and keeping hydrated are essential measures. Additionally, wearing light clothing and avoiding strenuous activities can help manage body heat. However, the question remains: how much of a role should humidity play in determining whether schools close or work is suspended during a heatwave?
The current heatwave has sparked renewed debate about the criteria for extreme weather alerts. Some argue that the “feels like” temperatures, rather than just air temperatures, should be the primary metric. This approach would better reflect the real-world impact on human health, as the combination of heat and humidity creates a more challenging environment. For example, even if the air temperature remains at 35°C, the added moisture could make it feel like 41°C, significantly increasing the risk for those who are already vulnerable.
As the planet continues to warm, heatwaves like this are expected to become more frequent and intense. The current conditions serve as a warning of what to come. With the potential for consecutive tropical nights and elevated humidity, the body’s ability to cope with heat is being tested like never before. The implications for public health are profound, underscoring the importance of adaptive measures to protect communities from the escalating effects of climate change.
Comparisons to past heatwaves reveal a worrying trend. The July 2022 event, while historically significant, was marked by dry air, which made the heat more manageable. In contrast, the current wave, driven by a moisture-laden heat dome, feels more oppressive. This shift in weather patterns highlights the growing complexity of heat-related challenges, as both temperature and humidity levels rise in tandem. The result is a more sustained and severe heat stress, which could have long-term consequences for health and wellbeing.
Ultimately, the combination of high temperatures, humidity, and prolonged tropical nights is creating a unique scenario that demands a more comprehensive response. Whether through individual actions or government interventions, the goal remains the same: to minimize the impact of this heatwave and prepare for future extremes. As the summer progresses, the focus will be on how well society can adapt to these increasingly severe conditions.
