The Met Office has taken the rare step of issuing a red, danger-to-life heat warning for central and southern England and Wales – only the second time it's deployed its highest alert for heat – with temperatures forecast to hit 40°C. The UK Health Security Agency (UKHSA) has also issued a red heat-health alert for six regions of England. Forecasters warn of consecutive tropical nights, transport disruption, and health impacts across the wider population and not just the vulnerable.
Put simply, the UK's summers are no longer occasionally warm; they are structurally hotter, and this week's weather rams this point home.
For general counsel and compliance leads, heatwaves of this intensity pose a tangle of legal, regulatory, and operational risks that cut across health and safety, employment law and contractual performance.
Health and safety
There is no maximum temperature for workplaces in the UK, so there's no specific temperature at which it becomes officially too hot to work. In May 2026, the Climate Change Committee recommended that the Government should "commit to a national maximum temperature for workplaces." At the moment, however, no such maximum is on the cards in Great Britain.
This doesn't mean employers can ignore the heat: employers are still required to provide a "reasonable" temperature in the workplace during working hours and manage health and safety risks. What is reasonable will depend on the workplace, the type of work and the employee's role. Employers should make sure they have up-to-date risk assessments for working during extreme weather, as well as travelling to work, and to take all reasonably practicable steps to minimise those risks.
Risk assessments should cover all of your workforce, including remote workers. They should consider the nature of work, the working climate and any work clothing or personal protective equipment. They should also take account of employees who may be vulnerable to heat. Travel risks should also be considered, particularly where travel is part of the role.
Although many employers will be reacting to this week's forecast, as we noted in our article here, businesses need to make extreme heat part of their long-term planning. Making heat protection measures a routine part of risk assessments will help employers prepare for future hot weather.
Your staff
The hot weather can cause difficulties both getting to work and when working.
Rail cancellations, speed restrictions on buckling tracks, and disrupted bus services can leave commuters delayed or even unable to reach their workplaces. Roads soften too: the AA has warned that gritters may need to be deployed this week to help fix road surfaces. It shouldn't be surprising, therefore, that the Met Office warns that "substantial changes in working practices and daily routines will be required".
Employers should communicate any extreme weather policies and ensure employees are clear on the expectations for attendance. Those communications should be sent early, be practical and avoid ambiguity: employees should know whether they are expected to travel, whether they may work from home, who they should contact if transport is disrupted and how pay or leave will be treated if they cannot attend.
Some employers may choose to encourage remote working during a heatwave, although this has its own challenges with employers still needing to assess the risks at home and put in place appropriate measures. Employers should be careful not to assume that home working is the safer or easier option for all: some employees may be working in poorly ventilated accommodation or rooms that become uncomfortably hot.
Employers will need to consider how different cohorts of their workforce are impacted, particularly for those who may be vulnerable. Heat may particularly affect pregnant workers, older employees, and those with certain medical conditions. A rigid attendance policy that fails to accommodate these groups during extreme heat could potentially amount to indirect discrimination or a failure to make reasonable adjustments.
Even if employees can safely get to your workplace employers will need to consider how they can manage the risks of heat discomfort and heat-related illness. This could include providing air-conditioning, fans, cold water dispensers, providing shaded areas or relaxing formal dress codes. If these types of measures won't adequately manage the risk, employers may need to consider increasing rest breaks, rotating duties, moving tasks away from the hottest times of the day, postponing any outdoor or physical work, or even a temporary shut-down. The heat will also have a significant impact on those who are required to wear protective clothing and employers should consider whether modifications can be made without compromising safety.
For those working from home, employers could consider checking that staff have a suitably ventilated or temperature-controlled room at home in which to work. Employers should consider reminding their staff how to stay cool and of the measures implemented to manage risk, such as allowing extra breaks.
Staff may also find themselves under extra pressure during extreme weather. For example, if schools close early or altogether, those who have childcare responsibilities may be faced with trying to find childcare at the last minute. Employees could utilise various rights to time off, such as annual leave or unpaid time off for dependants. Time off for dependants is intended to deal with emergencies, rather than to provide ongoing childcare, so employers should think in advance about how they will deal with repeat or longer-lasting weather events.
Cancelled events
The UK's summer calendar – from Wimbledon to music festivals, Royal Ascot to the Notting Hill Carnival – depends on weather that cooperates. Extreme heat can force cancellations, curtailments, or emergency interventions that trigger a cascade of contractual and regulatory consequences.
For businesses hosting events, the contractual position deserves close attention. Force majeure clauses drafted with storms, floods, and pandemics in mind often do not expressly cover extreme heat. Whether a heatwave amounts to an event "beyond reasonable control" depends on the clause's wording and the surrounding circumstances. For more information on force majeure, see here.
When a heatwave looks set to disrupt attendance at an event, businesses may want to consider shifting to remote or hybrid attendance if possible.
Contractual performance
Heat disrupts supply chains in numerous ways. Transport networks slow or stop. Power grids strain, threatening manufacturing output and data centre uptime. The Met Office says that in the current heatwave, there is a "high risk of failure of heat-sensitive systems and equipment, with the loss of power and other essential services, such as water, electricity, gas or mobile phone services."
Businesses with fixed delivery schedules or service-level commitments should review whether extreme heat could or is likely to trigger any issues. A supplier may seek to rely on force majeure where a heatwave prevents or delays performance, but the position will depend on the drafting, the causal link to the missed obligation, and compliance with notice and mitigation requirements. Where heatwaves are not expressly listed, the question is whether they fall within broader wording such as "extreme weather", "act of God" or "natural disaster".
Frustration will usually be harder to establish and is unlikely to apply where the heatwave merely makes performance more expensive, inconvenient or delayed, rather than impossible or radically different.
Heatwaves are no longer freak events. They have become a recurring feature of British summers, and their legal and commercial consequences will intensify. Businesses should ensure they plan in advance for such extreme weather. If you have any question on the above or need help understanding how to deal with extreme heat in your workplace or how your contracts may be affected, please get in touch.
