It’s Too Hot – But Legally, That’s Fine

At a Wimbledon semi-final today, play was paused twice in a single set as spectators required medical attention – both due to heat-related issues. The day wasn’t marked by any official warning or heatwave alert. It was simply warm, by British standards – around 30°C, sunny, and still. And yet, in those conditions, sitting relatively still in the shade was enough to cause fainting and illness.

The incident highlights a strange blind spot in how we think about temperature and public safety. The UK has clear guidance and even legislation for minimum temperatures in certain settings. The Workplace (Health, Safety and Welfare) Regulations 1992, for instance, suggest a minimum of 16°C for offices, rising to 13°C for active work. Schools, too, are monitored for cold, with temporary closures not uncommon during freezing spells. But there are no legal maximum temperatures – neither for classrooms, nor construction sites, nor care homes. The same goes for housing. We worry a great deal about people being cold. We rarely do the same about them being too hot.

And yet the risks of heat are real – and rising.

The health risks of heat are under-acknowledged

Even modest levels of heat can have serious health consequences, especially for older adults, people with heart conditions, and those working outdoors. High indoor temperatures are associated with increased risk of dehydration, fatigue, cognitive decline and cardiovascular strain. The UK Health Security Agency now regularly issues hot weather alerts under its Heat-Health Alert system, particularly for Level 3 conditions, typically triggered when temperatures are forecast to exceed 30°C by day and 15°C by night for two or more days.

In the 2022 summer heatwave, when the UK reached 40°C for the first time, there were an estimated 2,985 excess deaths among over-65s alone during the hottest days, according to the Office for National Statistics. Many of these deaths occurred not outdoors, but in homes, hospitals and care facilities that were simply too hot for the body to cope.

Homes built to keep heat in

One of the UK’s most significant vulnerabilities is our housing stock. Built primarily to retain heat and withstand cold winters, British homes are often poorly ventilated, lacking in shading, and constructed from materials that absorb and trap heat during warm spells.

This isn’t a criticism – our housing wasn’t designed for 35°C days, because such conditions were once extremely rare. But it is a reality we now need to address. Climate projections from the Met Office suggest that by 2070, the UK could see up to 50% more hot days (above 25°C) per year, alongside more frequent and intense heatwaves.

The government’s own Climate Change Committee has warned repeatedly that the UK is “woefully unprepared” for the impacts of rising temperatures, particularly in the built environment. Retrofitting homes for cooling – through shading, ventilation, reflective surfaces and urban greening – is rarely prioritised in current retrofit programmes, which still focus overwhelmingly on insulation for winter warmth.

Workplaces, schools and sports venues: no upper limit

It’s not just our homes that are unfit for the heat. There is no legally mandated maximum temperature for workplaces in the UK. The Health and Safety Executive (HSE) provides guidance, but it is vague: employers must ensure thermal comfort, take reasonable steps to manage heat, and consult with employees – but they are not required to take specific action at a particular temperature threshold.

By contrast, several EU countries do have upper limits. In Germany, for instance, if indoor temperatures exceed 26°C, employers must take action to reduce heat exposure – such as adjusting dress codes, shifting working hours, or providing cooling breaks. Spain has introduced restrictions on outdoor work during extreme heat, including bans on physical labour in certain industries when heat alerts are active.

Schools in the UK are also not required to close during high heat, despite research showing that learning and concentration drop significantly as classroom temperatures climb. There is some guidance suggesting adjustments after 30°C – but no enforceable protections.

FYI: Wet Bulb Globe Temperature (WBGT)

WBGT is a more accurate measure of heat stress than air temperature alone. It combines temperature, humidity, wind speed, sun angle, and cloud cover to estimate the actual risk to human health. A WBGT of 30 °C, for example, can be dangerous even if the air temperature is “only” 30 °C – especially for physical work or in direct sun. It’s widely used in sport and the military, but rarely referenced in UK public guidance.

Who suffers most?

As with so many climate-related risks, heat is not equally distributed. The impacts fall most heavily on those already vulnerable: the elderly, people with chronic health conditions, those living in high-density urban areas with little green space, or in upper-storey flats with poor ventilation. Outdoor workers, such as delivery drivers, agricultural labourers and construction staff, are often expected to continue as usual even when heat reaches unsafe levels.

This summer also highlighted heat’s hidden impact on public transport. In June, temperatures reached over 33 °C, and multiple Thameslink trains around South London stalled without air conditioning or power. Approximately 1,500–1,800 people had to be evacuated onto tracks in intense heat, with passengers describing the carriages as “like an oven” and being “slow-cooked”. One heroic local delivery driver even threw bottled water up to passengers stranded on a viaduct. These scenes reinforced that heat isn’t just an outdoor issue – it also shuts down vital infrastructure, endangering commuters and overstretching emergency services.

Unlike extreme cold, where disruption often sparks media coverage and policy response, heat tends to unfold quietly – until people are fainting, trapped, or overheating. We treat heat as a private discomfort or novelty, not as a systemic threat on par with cold.

Adaptation isn’t just about floods and droughts

There’s growing recognition that climate change requires adaptation as well as mitigation – but adaptation is often interpreted as something for farmers, engineers or coastal towns. In reality, adaptation means rethinking the basics of daily life: how we design homes, how we schedule work, how we manage public events, and how we protect the most vulnerable when the weather turns extreme.

The UK’s National Adaptation Programme has been criticised for lacking clear timelines, targets and funding. Yet it's in precisely these mundane gaps – in heat thresholds, building design, and workplace practice – that adaptation becomes real.

Towards a cultural shift

To make progress, we need to stop seeing heat as the harmless sibling of cold. We should establish clear, evidence-based upper temperature limits for schools and workplaces, expand retrofit funding to include cooling measures, and review public health guidance to reflect the realities of hotter summers. We don’t need to panic. But we do need to prepare.

The Wimbledon crowd incident wasn’t a crisis. No one died. Play resumed. But it’s a quiet signal – one of many – that we are entering a new normal in which 30°C days are no longer a rare treat, but a recurring challenge. We should be asking: are our homes, our policies, and our assumptions ready?

Because if we’re fainting whilst seated at 30°C, what happens when it hits 35?

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