Article

Preparing UK and European Workplaces for Extreme Heat

Extreme heat is a permanent workplace risk. Learn short-, medium-, and long-term actions to protect your workforce, reduce costs, and strengthen resilience.

Key takeaways:

Extreme heat is a permanent and worsening occupational health risk across the UK and Europe.
Employers are wise to take short-, medium- and long-term actions to protect their workforces, businesses, and value chains.

Extreme heat is now a business issue

Extreme heat is no longer a unique event. Across the UK and Europe it has become a recurring workforce risk, with measurable consequences for employee health, operational continuity, and employer liability.

The summer of 2022 marked a turning point: the UK recorded temperatures above 40°C for the first time, and across Europe, more than 60,000 people died from heat-related causes.¹ These figures are no longer anomalies. They are a new baseline. And for employers with workforces in the UK and EU, they represent a compounding and permanent operational challenge.

The risks go beyond heat illness

Extreme heat exacerbates respiratory and cardiovascular conditions. It also impairs cognition, coordination, and reaction time before workers experience any obvious symptoms of heat illness.²,¹⁰ That means extreme heat increases not only the risk of direct illness, but also the likelihood of broader workplace mistakes and injuries.

The business case for acting early is correspondingly strong. Hot days already cost the UK economy an estimated £1.2 billion in lost gross value added each year, and productivity falls by roughly 2% for every degree above 24°C.³ At the European level, annual losses from heat stress could reach €563 billion, ~1.15% of GDP, by the 2080s.⁴

The costs of inaction extend well beyond productivity, spanning: reduced output, absenteeism, medical expenses, and potential workers' compensation liability.

Heat preparedness is also increasingly relevant from a legal and compliance standpoint. At the EU level, the Framework Directive 89/391/EEC requires risk assessment for all workplace hazards, including heat, and individual member states are moving well beyond that baseline. ⁶ For example, Spain's Royal Decree-Law 8/2024 obligates all Spanish employers to have active protocols for adverse weather conditions including heatwaves.¹¹

For UK and European employers, this is no longer a question of seasonal inconvenience. The health, productivity, and liability consequences are already measurable, and the regulatory environment is moving to match.

What organizations can do now: short-term actions

The first step is a shift in mindset: extreme heat is a recurrent operating condition, not an anomaly to manage reactively. Concrete heat illness prevention protocols are a clear starting point. These include:

Ensuring access to cool drinking water at all times, with workers prompted to hydrate before thirst develops
Building structured work-rest cycles that reduce continuous exertion during peak heat hours
Providing formal symptom recognition training so that workers and supervisors can identify early signs of heat exhaustion before they escalate to heat stroke
Shifting physically demanding tasks to early morning where possible
Providing shaded or cooled rest and recovery spaces
Rotating workers through high-heat roles to limit cumulative exposure

Onboarding protocols deserve particular attention. Research indicates that 70% of heat-related deaths on the job occur during a worker’s first week of employment.⁹ Older workers, those with chronic conditions, and pregnant employees are disproportionately vulnerable: identifying these groups in advance allows for appropriate planning rather than reactive management.

Make heat planning part of the risk management framework

Heat planning is most effective when embedded in an organization's broader risk framework rather than managed as a standalone seasonal checklist: heat protocols treated as live, auditable documents, reviewed against local legal requirements and aligned to business continuity planning.

Organizations that build heat risk into standard risk management practice now, rather than waiting for national legislation to mandate specific steps, will find themselves ahead of the curve.

Building resilience for the medium term

Beyond immediate protective measures, there is a growing case for investing in longer-lasting heat resilience. Wearable sensors that monitor body temperature and heart rate are already in use in some industries, alerting workers and supervisors before conditions become dangerous.

Retrofitting workplaces for cooling is a growing medium-term priority. The International Energy Agency projects the number of room air conditioning units in use across Europe to triple by 2050, and the UK Climate Change Committee has flagged cooling as a priority adaptation challenge.¹² Reviewing whether current facilities, including vehicles and field-based operations, have adequate cooling capacity is a reasonable near-term planning exercise.

Benefits strategy is worth reviewing in this light. Marsh’s People Risk 2026 data shows that UK employers’ top climate planning priority is already ensuring that health benefits cover climate-related conditions (36%); in Europe, the equivalent priority is supporting employees in securing sufficient personal insurance against climate threats (41%).⁵ Forward-thinking organizations are reviewing whether current arrangements are fit for that purpose: whether health and protection benefits adequately address heat-induced illness, and whether personal insurance products, particularly for home and property, are being flagged to employees in climate-vulnerable locations.

Plan for a hotter future

The UK Met Office projects that 40°C days could become a regular occurrence every three to four years by 2100 under high-emissions scenarios.⁷ Against this backdrop, long-term workforce strategy is well served by accounting for heat as a structural risk, not a tail event.

The questions worth asking now: which roles, locations, and operations are most exposed; what disruption looks like over a five- or ten-year horizon; and whether heat impacts on supply chain dependencies, including logistics, infrastructure, and key suppliers, are adequately factored into continuity planning.

Managing exposure now puts organizations in a far stronger position than those who wait for the risk to materialize.

The bottom line

According to Marsh’s forthcoming Survey on Health and Benefit Strategies for 2027, 78% of employers with more than 500 employees will have one or more policies or programs in place to address climate risks for the workforce in the next year.⁸ The momentum is building. The question for UK and European employers is no longer whether extreme heat will affect the workforce, but how well-prepared the organization will be when it does.

Employers that act early, treating heat as the permanent operational reality it has become, will be better placed to protect their people, reduce avoidable costs, and strengthen organizational resilience.

What to do next

Start by assessing which parts of the workforce, by location, role, and vulnerability profile, face the greatest exposure. Then benchmark current heat protocols and business continuity plans against emerging best practice.

For organizations that want to go further, Marsh can support with heat risk assessments, insurance coverage gap analysis, and business adaptation strategies across operations and supply chains. Read more here.

Sources

¹ Ballester, J. et al. (2023). ‘Heat-related mortality in Europe during the summer of 2022.’ Nature Medicine. Updated estimates: Ballester et al., Lancet Regional Health – Europe, 2024.

² World Economic Forum / Mercer. ‘How we should adapt our workplaces to cope with extreme heat.’ Mercer Insights, 2024. mercer.com

³ Grantham Research Institute on Climate Change and the Environment, London School of Economics. ‘Heat and productivity in the UK.’ 2024. Also: Somanathan et al. (2021), American Economic Review.

⁴ European Environment Agency (EEA). Climate-related economic losses in Europe. 2024 projections.

⁵ Marsh. People Risk 2026: The Human Edge. Survey of 4,517 HR and Risk professionals across 26 markets, conducted October–November 2025.

⁶ EU Framework Directive on Health and Safety at Work (89/391/EEC). EU Workplace Directive 89/654/EEC.

⁷ UK Met Office. UK Climate Projections (UKCP). Met Office, 2024.

⁸ Mercer. Survey on Health and Benefit Strategies for 2027. Survey of 604 organisations conducted April–May 2026; results based on 481 organisations with 500 or more employees. Publication forthcoming.

⁹ Health Action Alliance / National Commission on Climate and Workforce Health. ‘How To Protect Your Employees From Extreme Heat.’ June 2024.

¹⁰ Health Action Alliance / National Commission on Climate and Workforce Health. ‘New Study: As Heat Rises, So Do Workplace Injuries.’ November 2024.

¹¹ Spain: Royal Decree-Law 8/2024, Boletín Oficial del Estado. Greece: Ministry of Labour and Social Affairs mandatory circulars on heatwave working conditions, 2025.

¹² IEA, Electricity 2025 (February 2025), iea.org/reports/electricity-2025; Eurostat household energy dataset nrg_d_hhq; UK Climate Change Committee adaptation reports.