Category: Health & Safety | Reading time: 6 min | Published: June 2026
Every summer, UK employers make the same costly mistake: they wait.
They wait for the first complaint. They wait for the first incident. They wait for the first enforcement notice. By then, the damage is already done — to their workers, their reputation, and their bottom line.
Heat stress is not a seasonal nuisance. It is a foreseeable, manageable, and legally actionable workplace hazard. And in 2026, with UK summers breaking temperature records and the Health and Safety Executive increasing scrutiny of thermal risk management, employers who still lack a heat stress policy are running out of excuses.
This guide is written specifically for business owners, HR managers, operations directors, and anyone responsible for a workforce. Not as a health and safety checklist — but as a frank assessment of what inaction actually costs you.
The Business Case for Acting Now
Let's start with money, because that is often what moves decisions.
Workplace accidents and work-related ill health cost UK employers billions of pounds every year in lost productivity, compensation claims, increased insurance premiums, and regulatory penalties. Heat-related illness is among the most preventable causes of that cost — yet it remains chronically undertrained.
Consider what a single heatstroke incident could mean for your business:
- Lost working days while the affected employee recovers — potentially weeks or months
- Agency or temporary staff costs to cover their absence
- An HSE investigation triggered by the incident report
- Potential prosecution under the Health and Safety at Work Act 1974 if controls were absent
- Civil claims from the injured worker or their family
- Reputational damage if the incident becomes public — increasingly likely in the age of social media
None of this is hypothetical. Courts and employment tribunals are increasingly ruling against employers who failed to conduct thermal risk assessments, failed to provide adequate rest breaks, or failed to train their supervisors to recognise the signs of heat illness.
The cost of a half-day heat stress awareness course for your supervisors? Negligible by comparison.
What the Law Actually Expects of You
There is a common misconception that because the UK has no maximum legal working temperature, employers have no specific duties around heat. This is wrong — and it is a misreading that has cost businesses dearly.
Three pieces of legislation apply directly:
The Health and Safety at Work Act 1974 places a general duty on every employer to protect workers from all foreseeable harm. A heatwave in June is foreseeable. A warehouse reaching 35°C in July is foreseeable. The question enforcement officers and courts ask is not whether a maximum temperature was breached — it is whether the employer took reasonable steps to manage a risk they should have anticipated.
The Workplace (Health, Safety and Welfare) Regulations 1992 require that indoor temperatures be kept at a "reasonable" level during working hours. Thermometers must be available. Employers must take steps when temperatures become uncomfortable or unsafe — long before anyone collapses.
The Management of Health and Safety at Work Regulations 1999 require employers to formally assess all significant risks and implement controls. Heat is a significant risk for large parts of the UK workforce from May through September. If it is not in your risk register, it should be.
The legal standard is not perfection. It is reasonableness. But "we didn't know" and "we didn't think it was that serious" are not reasonable defences when the HSE has been publishing guidance on thermal comfort for decades.
Which Workers Are You Most Responsible For?
Not every employer faces the same level of heat risk — but more do than realise it. Ask yourself whether any of your workforce falls into these categories:
Outdoor workers are the most obvious group. Construction, landscaping, agriculture, utilities, logistics, and delivery drivers all spend extended periods in direct sunlight. In 2026, UK summers regularly push temperatures into the low-to-mid thirties, and solar radiation adds considerably to the perceived heat load.
Indoor workers in hot environments are frequently overlooked. Commercial kitchens, bakeries, laundries, foundries, warehouses without climate control, and factories with hot machinery can reach dangerous temperatures even on moderately warm days. Workers in these environments may actually be at greater risk than outdoor workers because ventilation is often poor.
Workers in PPE or heavy clothing face additional risk because their protective equipment prevents the body from cooling itself effectively through sweating. This is particularly relevant in sectors like manufacturing, construction, and food processing.
New starters and returning workers are at elevated risk during the first two weeks in a hot environment, before the body has acclimatised. If you take on seasonal workers in summer — as many construction, agricultural, and logistics businesses do — this group needs specific attention.
Older workers, pregnant workers, and those with underlying health conditions including heart disease, respiratory conditions, and certain medications face greater physiological risk from heat. Your risk assessment must account for individual vulnerability, not just average conditions.
The 5 Things Every Employer Should Have in Place Before July
This is not an exhaustive compliance checklist. It is the minimum your business should have in place before peak summer temperatures arrive.
1. A written thermal risk assessment Identifying which roles, locations, and individuals face heat risk; what the controls are; and who is responsible for reviewing it when forecasts warn of extreme heat. If you don't have one, this is your most urgent action.
2. Engineering controls where possible Fans, improved ventilation, repositioned workstations, insulated surfaces, shading for outdoor workers. These do not have to be expensive. A well-placed industrial fan in a warehouse can make the difference between a safe environment and a dangerous one.
3. A rest breaks and hydration policy Workers in hot conditions should have access to cool water at all times — at least 250ml per hour is the recommended minimum. Shaded or cool rest areas must be available. This is an administrative control, but it is also a legal expectation under the Workplace Regulations.
4. Trained supervisors and first aiders This is the single most impactful investment you can make. A supervisor who can recognise the early signs of heat exhaustion and act immediately can prevent a minor incident from becoming a serious one. A first aider who knows how to respond to heatstroke can save a life. Neither of these things happens without training.
5. An acclimatisation plan for new starters Any worker new to a hot environment — whether a new employee, a seasonal worker, or someone returning from a long absence — should have their heat exposure built up gradually over 7 to 14 days. This is one of the most evidence-based interventions for preventing heat illness and one of the most commonly skipped.
The Training Your Team Needs
Training is where good intentions become real capability. Here are the most relevant courses available through Envicourse:
Workplace Health & Safety — E-learning A solid foundation for all staff covering general health and safety principles, hazard recognition, and employer and employee responsibilities. Ideal as part of onboarding or as a refresher before summer.
Health, Safety & Care Courses — Full Range Browse the complete catalogue of health and safety training including risk assessment, first aid, manual handling, and occupational health. Suitable for individuals and teams across all sectors.
Health and Safety Courses Accredited qualifications and short courses covering everything from basic awareness through to advanced management-level training. Includes options for managers, supervisors, and directors.
First Aid Training Equipping your first aiders to respond to heat exhaustion and heatstroke is non-negotiable for any business with outdoor or hot-environment workers. First aid training covers recognition, immediate response, and when to escalate to emergency services.
Highfield Health & Safety Level 3 — E-learning A comprehensive management-level qualification covering health and safety law, hazard identification, and control measures. Ideal for managers and supervisors who need a deeper understanding of their legal responsibilities, including thermal risk.
NVQ Health and Safety For those looking to build or formalise a career in health and safety management. NVQ qualifications demonstrate competence to employers, insurers, and regulators.
What Good Looks Like — And What It Costs to Get There
The most common objection to investing in health and safety training is cost. But consider what good heat stress management actually requires at the employer level:
- A risk assessment update: a few hours of a competent person's time
- An e-learning course for supervisors: often under £50 per person
- A first aid refresher: a half-day course
- A hydration policy and some fans: minimal capital outlay
Set against the cost of a single serious incident — lost productivity, absence, claims, investigations, potential fines of up to £10 million for the most serious breaches under the Corporate Manslaughter and Corporate Homicide Act 2007 — the return on investment is not even a close call.
The businesses that get this right are not spending more than those that get it wrong. They are spending smarter, and earlier.
One Final Thought for Employers
The law sets a floor, not a ceiling. Meeting your minimum legal obligations around heat stress is the starting point — not the goal. The employers who genuinely protect their people go further: they build a culture where workers feel safe to say they are struggling, where supervisors act without being told, and where heat is treated with the same seriousness as any other occupational hazard.
That culture does not come from a policy document. It comes from training, leadership, and consistent action — starting before the first heatwave warning of the summer.
Don't wait.
Browse all health and safety courses at envicourse.com or call us on 0808 1966 830.
Related reading: Workplace Health & Safety courses | Health, Safety & Care training | NVQ Health and Safety