In May 2026, the UK broke its all-time May temperature record twice in two days, with Kew Gardens reaching a provisional 35.1°C.1 The Met Office confirmed that extreme heat events of this magnitude are now roughly three times more likely due to human-caused climate change. These trends highlight the urgent need for businesses to adapt to hotter working conditions.
Why is heat becoming a greater risk for construction businesses?
While many workers are accustomed to operating outdoors throughout the year, excessive heat can create significant health, safety and operational challenges that can impact both individuals and businesses. Construction workers are particularly vulnerable to heat-related illnesses due to the physical nature of their work, prolonged exposure to direct sunlight and the additional burden of wearing personal protective equipment (PPE). A 2025 study conducted by the University of Reading revealed that 44% of construction site workers reported experiencing heat-related illnesses, underscoring the severity of the issue.2 Even on moderately warm days, strenuous activity can lead to dehydration, fatigue and reduced concentration. During heatwaves, the risks increase significantly, with workers potentially suffering from heat exhaustion or, in severe cases, heatstroke.
The impact of extreme heat on site safety
Beyond the immediate health implications, fatigue and impaired judgement can increase the likelihood of accidents on site, creating wider safety concerns for employers and project stakeholders. According to a study by the British Safety Council, workplace accidents are 7% more likely to occur during periods of extreme heat.3 Additionally, research by the International Labour Office in 2025 found that extreme heat could reduce quarterly labour productivity growth by 1.5 percentage points in the UK during a four-day heatwave.4 Construction is one of the sectors most affected by heat-related productivity losses, highlighting the economic impact of failing to address heat risks.
The wider operational and commercial implications
From a risk management perspective, hot weather should not be viewed as an isolated health and safety issue but as part of a broader operational risk landscape. Businesses that fail to adequately prepare for extreme temperatures may face reduced productivity, increased absenteeism, project delays and potential liability exposures.5 In an industry where tight deadlines and contractual obligations are commonplace, even a short period of disruption can have financial consequences. For example, a 2021 report by the Chartered Institute of Building (CIOB) found that weather-related delays, including those caused by heat, cost the UK construction industry an estimated £1 billion annually.5
How can employers manage heat-related risks effectively?
Effective management begins with planning. Employers should consider heat-related risks as part of their routine site risk assessments, evaluating factors such as temperature forecasts, task intensity, site conditions and worker welfare arrangements. Measures such as adjusting working hours to avoid the hottest parts of the day, increasing rest breaks and ensuring access to shaded areas can help reduce exposure while maintaining productivity. The most successful organisations are often those that proactively adapt their operations rather than reacting once problems arise.
Hydration is critical to preventing heat-related illness
Hydration also plays a critical role in preventing heat-related illnesses. Workers should have easy access to cool drinking water throughout the day and be encouraged to drink regularly, even before they feel thirsty. Creating a workplace culture where employees feel comfortable taking hydration breaks and reporting symptoms of heat stress is equally important. Supervisors should remain vigilant and recognise the early warning signs of heat-related illness, including dizziness, headaches, nausea and unusual fatigue.
Are your workers trained to recognise the signs of heat stress?
Training and communication are key components of any effective heat management strategy. When workers understand the risks associated with high temperatures and know what symptoms to look for, they're better equipped to protect themselves and their colleagues. Clear site procedures, regular toolbox talks and ongoing monitoring can help ensure that heat-related risks remain front of mind during periods of extreme weather. In July 2025, advocates at the Global Climate and Health Summit raised concerns about the lack of formal protections for workers during heatwaves, emphasising the challenges faced by construction workers, who often have to choose between protecting their health and maintaining their income.6
Heat risk is a long-term business challenge
The increasing frequency of extreme weather events means that heat risk is likely to become a more prominent issue for the construction sector in the years ahead. Unite, a major UK union, has called for a statutory maximum working temperature of 27°C for strenuous jobs like construction.7 This follows growing concerns about the risks of heat exhaustion, heatstroke and skin cancer among workers. Organisations that integrate heat management into their wider risk management framework will be better positioned to protect their workforce, maintain project continuity and minimise disruption. Taking a proactive approach not only demonstrates a commitment to employee wellbeing but also strengthens operational resilience and supports long-term business performance.
Key questions about working in heat
What are the signs of heat exhaustion?
Common symptoms include dizziness, headaches, excessive sweating, nausea, fatigue, muscle cramps and weakness. If left untreated, heat exhaustion can develop into heatstroke, which requires emergency medical attention.
What should employers do during a heatwave?
Employers should review risk assessments, adjust work schedules where possible, provide additional breaks, ensure access to drinking water and shaded areas, and monitor workers for signs of heat stress.
Why is heat management important for construction businesses?
Effective heat management helps protect employee wellbeing, reduce accident risks, minimise project disruption and support productivity during periods of extreme weather.
How can Gallagher help?
Managing construction risks requires more than reacting to immediate challenges, it requires a strategic approach that helps protect your people, projects and reputation. Gallagher's construction specialists work with businesses across the sector to identify emerging risks, strengthen risk management programmes and develop insurance solutions tailored to the unique needs of the construction industry.
To find out how Gallagher can support your business, contact one of our Construction specialists today.
