Heat in the Workplace
High workplace temperatures are more than an issue of comfort. Learn how heat affects safety, concentration, wellbeing, and employer responsibilities during hot weather.
Employer legal duties, first aid requirements, and practical heat management for HR, health and safety, and line managers
Updated 26 June 2026 to reflect this week's record-breaking heatwave.
This week the Met Office issued Red Extreme Heat Warnings across three consecutive days, Wednesday 24 to Friday 26 June, the first time this has happened since the current warning system began. Separately, and under a different alert system, the UK Health Security Agency extended only its second ever red heat-health alert, covering six English regions until Friday 26 June; the first was in July 2022.
The heatwave has provisionally broken the UK's June temperature record twice this week, climbing from 36.1°C at Gosport on 24 June to 36.4°C at Yeovilton on 25 June, both exceeding the previous June record of 35.6°C, reached on 28 June 1976 and 29 June 1957. High humidity has made conditions feel more oppressive than the dry heat of the July 2022 record heatwave, increasing the risk of heat stress even for fit, healthy adults.
This comes only weeks after the UK's all-time May temperature record was broken twice in two days, with Kew Gardens reaching a since-verified 35.1°C on 26 May 2026. Two record-breaking heat events in the space of a month are consistent with the pattern climate scientists have warned employers to expect, not a one-off anomaly.
For most UK employers, workplace heat has historically been treated as a minor seasonal inconvenience. That framing is no longer adequate. Extreme heat is becoming a recurring feature of the UK working year, not an occasional anomaly, and the legal framework governing employer responsibility already applies to it in full, without needing to change.
This guide is structured in two parts. The first covers the current legal position clearly and practically. The second covers the practical measures employers are expected to take, including first aid response. Both are relevant to HR managers, health and safety leads, and line managers with responsibility for teams.
This guide does not constitute legal advice
The legal summaries below reflect current statute and HSE guidance as of May 2026. Employers with specific concerns about compliance or liability should take qualified legal advice.
Part One: The Legal Position
Is There a Legal Maximum Temperature for Working in the UK?
No. The UK currently has no legal maximum temperature for indoor or outdoor workplaces.
The HSE’s position is that no single upper limit could apply sensibly across all workplaces, because some industries, such as bakeries, foundries and glass manufacturing, operate at high temperatures as a matter of course. A threshold that worked for an office would be unworkable, or simply ignored, in a foundry.
This position is frequently misread as meaning employers have no specific duty in hot weather. That is incorrect, and the misreading creates genuine legal exposure.
The absence of a maximum temperature is not a legal safe harbour
Employers who take no action during a heatwave on the basis that no maximum temperature exists are misreading the law. The duty to maintain a reasonable temperature and to manage heat as a foreseeable hazard remains fully in force.
The Legislative Framework
Four pieces of legislation are directly relevant to employer duties in hot weather. Each imposes distinct obligations.
Employer Legal Duties: Heat in the Workplace
| Legislation | What It Requires | Consequence of Failure |
|---|---|---|
| Health and Safety at Work etc. Act 1974, s.2(1) | Employers must ensure, so far as is reasonably practicable, the health, safety and welfare of all employees. Heat risk is explicitly covered by this general duty. | Criminal prosecution. Unlimited fines. Custodial sentences for directors in serious cases. |
| Workplace (Health, Safety and Welfare) Regulations 1992, Reg. 7 | Indoor workplaces must maintain a reasonable temperature during working hours. No statutory maximum, but 'reasonable' is assessed by HSE inspectors. | Enforcement notice. Prohibition notice. Prosecution if a worker suffers harm. |
| Management of Health and Safety at Work Regulations 1999, Reg. 3 | Employers must carry out suitable and sufficient risk assessments covering all foreseeable hazards, including heat. Assessments must be reviewed when conditions change. | Failure to risk-assess is itself a breach. Evidence of no assessment damages employer position significantly in civil claims. |
| Health and Safety (First Aid) Regulations 1981 | Employers must provide adequate and appropriate first aid equipment, facilities, and personnel. Heat illness response must be within first aid capability. | HSE can issue improvement notices. Evidence of inadequate first aid provision relevant in civil claims. |
What Does ‘Reasonable Temperature’ Mean Under UK Law?
Regulation 7 of the Workplace (Health, Safety and Welfare) Regulations 19922 requires indoor temperatures to provide ‘reasonable comfort without the need for special clothing’. No specific maximum figure is set.
When HSE inspectors assess whether a workplace temperature was reasonable, they consider the full picture: whether a risk assessment was carried out, whether control measures were implemented, whether workers raised concerns, and what action was taken in response. An employer who does nothing during a heatwave and subsequently has a worker suffer heat exhaustion or heatstroke is in a significantly worse position than one who implemented appropriate measures even if those measures did not fully prevent harm.
The TUC has called for employers to take action when temperatures rise above 24°C and workers feel uncomfortable, and has proposed a legal maximum of 30°C, or 27°C for strenuous work, rather than a single comfort threshold.15 HSE confirmed in June 2026 that it is progressing a review of the guidance and Approved Code of Practice behind the 1992 Regulations, to ensure it reflects a modern workplace16, alongside a June 2025 House of Lords debate on whether a fresh review was needed and a 2024 Labour manifesto commitment to modernise heat guidance.3 Legislative or guidance change remains possible. Whether or not a maximum is eventually introduced, the existing framework already requires active management of heat risk.
What Must a Heat Risk Assessment Cover?
A heat risk assessment must identify which roles, locations or tasks create elevated heat risk, what control measures are in place, and which workers face greater risk due to health conditions, medication or lack of acclimatisation.
Regulation 3 of the Management of Health and Safety at Work Regulations 19994 requires this for all foreseeable hazards, and hot weather is foreseeable. An employer who has not assessed heat risk cannot credibly claim to have met their duty of care.
The assessment is not a one-time document. When conditions change significantly, including during a heatwave or when the UKHSA issues a heat-health alert, the assessment should be reviewed and control measures adjusted accordingly.
Heat sits alongside other foreseeable hazards under this same duty. Employers who already run a stress risk assessment process under the HSE Management Standards, can extend the same structure to cover heat rather than building a separate process from scratch.
Acclimatisation matters
New workers and those returning after absence are at higher risk during their first days in hot conditions. HSE guidance recommends introducing them to the full workload gradually over one to two weeks.
What Are an Employer’s First Aid Duties for Heat Illness?
Employers must provide first aid personnel, equipment and facilities adequate to respond to heat exhaustion and heatstroke, under the Health and Safety (First Aid) Regulations 1981.5
What constitutes adequate first aid provision is determined by the size and nature of the organisation, the hazards present, and the number of employees. During a heatwave, the risk of heat illness rises materially. An employer whose first aid provision was adequate under normal conditions should consider whether it remains adequate when temperatures are exceptional.
Specifically, the designated first aider or appointed person must be capable of recognising and responding to heat exhaustion and heatstroke. These are not niche or specialist conditions during a UK heatwave in 2026: they are foreseeable emergencies. If first aiders are not confident recognising and responding to heat illness, employers should treat that as a gap in their current first aid arrangements.
Employers checking whether their current provision covers this should look at syllabus content directly rather than assuming. Our First Aid at Work course includes recognition and response to heat exhaustion and heatstroke as standard content, not an add-on. Our Emergency First Aid at Work course, now includes extreme heat as well.
A note on enforcement
HSE inspectors can enter workplaces without notice, issue improvement and prohibition notices, and bring criminal prosecutions. Breaches of the Health and Safety at Work Act carry unlimited fines for organisations and can result in custodial sentences for directors and senior managers in cases of serious failure.
Civil claims for compensation from workers who suffer heat illness are a separate and additional exposure. Evidence of a failure to risk-assess or implement control measures is highly relevant in such claims.
Part Two: Practical Heat Management
What Should Employers Do to Reduce Heat Risk?
HSE guidance points to four areas of action: environmental controls, work pattern adjustments, hydration, and clear communication, set out in HSE’s INDG451 guidance, ‘Heat stress in the workplace’6.
Employers do not need to apply every measure in every workplace, but they do need to show that heat risk has been assessed and suitable controls have been considered and implemented. These are the measures HSE inspectors expect to see evidenced in a proportionate response to a foreseeable hazard.
Environmental controls
- Provide adequate ventilation. Open windows, use fans, and deploy air conditioning where available.
- Close blinds and curtains on south and west-facing windows during peak sun hours to reduce solar heat gain.
- Reduce heat-generating equipment use where practicable.
- Identify cooler areas of the workplace and make them accessible as rest spaces.
Work pattern adjustments
- Schedule physically demanding or outdoor work during cooler parts of the day, typically before 11am or after 3pm.
- Introduce additional rest breaks in cool areas and rotate tasks to reduce individual heat exposure.
- Consider whether any work can be deferred until conditions improve.
- Do not penalise workers who raise concerns about thermal comfort or request breaks.
Hydration
- Provide free access to cool drinking water at all times. This is an explicit expectation in HSE guidance.
- Actively encourage workers to drink regularly, not just when thirsty. By the time thirst develops, dehydration is already present.
- Avoid relying solely on vending machines or paid options: access should be free and without barriers.
Communication
- Brief line managers on the signs and symptoms of heat exhaustion and heatstroke before and during heatwaves.
- Communicate the heat management plan to all staff. Workers should know where to find water, where to rest, and who to report concerns to.
- Monitor UKHSA heat-health alerts and adjust measures accordingly when alerts are upgraded.
Employer Heat Action Checklist
| Before a Heatwave | During a Heatwave | If a Worker Falls Ill |
|---|---|---|
| Review and update your heat risk assessment | Monitor weather forecasts and UKHSA heat-health alerts | Move the worker to the coolest available space immediately |
| Ensure first aid personnel are trained in heat illness recognition and response | Increase ventilation: open windows, use fans, deploy air conditioning where available | Remove excess clothing and loosen tight items |
| Identify workers at greater risk (those on medication, with health conditions, new starters not yet acclimatised) | Provide free access to cool drinking water throughout the day | Cool the skin with cool (not ice-cold) water. Focus on neck, armpits, and groin |
| Confirm cool rest areas are accessible | Reschedule physically demanding tasks to cooler parts of the day where practicable | Give cool water to drink if the worker is conscious and able to swallow |
| Communicate heat safety procedures to all staff and line managers | Introduce additional rest breaks and rotate tasks to reduce heat exposure | Call 999 if not improving within 30 minutes, confusion develops, or skin is hot and dry |
| Review first aid kit contents and confirm adequacy | Actively check on workers who are alone or in high-risk areas | Do not leave the worker alone. Record time of onset and actions taken |
What Are the Signs of Heat Exhaustion?
Heat exhaustion causes heavy sweating, pale and clammy skin, headache, dizziness, nausea, muscle cramps, and a rapid weak pulse. The affected worker is usually still conscious and able to communicate.
Heat exhaustion occurs when the body is under severe thermal strain but has not yet failed to regulate its core temperature.
First aid response: heat exhaustion
Move the worker to the coolest available space immediately.
Remove excess clothing and loosen anything restrictive.
Cool the skin with cool water. Focus on neck, armpits, and groin.
Give cool water to drink in small, regular amounts.
Monitor continuously. If not improving within 30 minutes, or if confusion develops: call 999.
Do not leave the worker alone.
What Are the Signs of Heatstroke?
Red flags for heatstroke include a very high temperature, hot skin without sweating or skin that turns hot and dry, confusion, loss of coordination, seizure, or loss of consciousness. No single sign on its own is diagnostic; together, they mean treat it as heatstroke.
Heatstroke is a life-threatening emergency. The body’s thermostat has failed.
Hot, dry skin, confusion, convulsions or loss of consciousness are signs of heatstroke. It can be fatal if not caught early.13 Call 999.
While waiting for the ambulance: move to the coolest space, remove outer clothing, wrap in a cold wet sheet and pour cold water over it continuously.
Apply ice packs or cold packs wrapped in cloth to armpits, groin, and neck.
If unconscious: recovery position. Continue cooling until the ambulance arrives.
Do not give paracetamol or aspirin. Do not leave the worker alone.
Record time of onset and actions taken for the ambulance crew.
What Line Managers Need to Do
Legal responsibility rests with the employer, but line managers are the operational interface. Their decisions during a heatwave directly affect both worker safety and the organisation’s compliance position. Managers should be briefed clearly on the following:
- You are expected to act on heat concerns raised by workers. Dismissing complaints about temperature as oversensitivity is not a defensible position if a worker subsequently becomes ill.
- If a worker appears unwell during hot weather, do not wait for them to ask for help. Ask directly, act promptly.
- Ensure breaks are actually taken, not pressured away. Workers who skip rest breaks in high heat face elevated risk.
- Do not discourage workers from removing excess clothing or using fans. Practical cooling is not a discipline issue.
- If you are uncertain whether a worker needs medical attention, call 999. The consequences of under-responding to heatstroke are severe and irreversible.
Record Keeping and Documentation
In the event of a heat-related illness incident, the employer’s documentation will be scrutinised. The following records are relevant to both HSE investigation and civil claims:
- The current heat risk assessment and the date it was last reviewed.
- Evidence that control measures were communicated to staff and line managers.
- Records of UKHSA heat-health alert monitoring and any operational changes made in response.
- The first aid incident report, including time of onset, symptoms, actions taken, and outcome.
- Training records confirming that first aiders were trained in heat illness recognition and response.
An organisation that can demonstrate a systematic, documented approach to heat risk management is in a materially better position than one that cannot, regardless of the outcome of any individual incident. Documentation is not bureaucracy in this context: it is the evidence of compliance.
Workplace heat is a risk management responsibility, not a seasonal inconvenience. The legal framework is clear, the climate trend is unmistakeable, and the consequences of inadequate preparation fall on both the worker and the organisation.
This guide focuses on the employer's legal position and operational responsibilities. For a detailed clinical guide to heat-related illness, including how to recognise and treat dehydration, heat exhaustion, and heatstroke, and a dedicated section on children and babies, the full public guide is available here: https://blog.constellationtraining.co.uk/heat-related-illness-guide/
Constellation Training provides FAIB-accredited first aid training for workplaces throughout the UK, including in-house courses for organisations that want their first aiders confident with realistic workplace emergencies, including heat-related illness. Details of upcoming open and in-house options are available on our website.
References
[1] Health and Safety Executive. ‘Temperature in the workplace’. Available at: www.hse.gov.uk/temperature
[2] Workplace (Health, Safety and Welfare) Regulations 1992, Regulation 7 and Approved Code of Practice. Available at: www.legislation.gov.uk
[3] House of Lords debate on UK extreme heat preparedness, June 2025, Hansard; Labour Party General Election Manifesto 2024, health and safety commitments. Available at: labour.org.uk/change
[4] Management of Health and Safety at Work Regulations 1999, Regulation 3. Available at: www.legislation.gov.uk
[5] Health and Safety (First Aid) Regulations 1981. Available at: www.legislation.gov.uk
[6] Health and Safety Executive. ‘Heat stress in the workplace’ (INDG451). Available at: www.hse.gov.uk/pubns/indg451.htm
[7] Health and Safety at Work etc. Act 1974, Section 2(1). Available at: www.legislation.gov.uk
[8] Met Office. ‘UK May and spring temperature record provisionally broken for second day in a row’, May 2026. Available at: www.metoffice.gov.uk
[9] Met Office. ‘May 2026 temperature records verified’, June 2026. Available at: www.metoffice.gov.uk/blog
[10] Met Office. ‘Met Office issues Red Warning for Extreme Heat for record third consecutive day’, June 2026. Available at: www.metoffice.gov.uk
[11] Met Office. ‘UK June maximum temperature record provisionally broken’, June 2026. Available at: www.metoffice.gov.uk
[12] UK Health Security Agency. ‘UKHSA extends red heat-health alerts across England’, GOV.UK, June 2026. Available at: www.gov.uk
[13] Health and Safety Executive. ‘Temperature in the workplace: Heat stress’. Available at: www.hse.gov.uk/temperature/employer/heat-stress.htm
[14] Met Office (@metoffice). Confirmation of 36.4°C at Yeovilton, provisional June record, 25 June 2026. Available at: x.com/metoffice
[15] Trades Union Congress. ‘Working in extremes of temperature (hot or cold)’. Available at: www.tuc.org.uk
[16] Health and Safety Executive. ‘Risks to workers from extreme heat must be managed’, HSE Media Centre, June 2026. Available at: press.hse.gov.uk
