A thermometer reading does not decide whether work is safe. An office at 28°C, a busy kitchen at 28°C and a worker wearing impermeable PPE at 28°C create very different risks. Employers need to understand the legal benchmarks, assess the actual work and put controls in place before discomfort becomes heat stress, cold stress or unsafe behaviour.
Is there a legal minimum or maximum workplace temperature?
The Workplace (Health, Safety and Welfare) Regulations 1992 require the temperature inside buildings to be reasonable during working hours. What is reasonable depends on the work, the environment and the people exposed. The law does not set one maximum temperature at which everyone must stop work.
HSE explains that the Approved Code of Practice suggests indoor workplaces should normally be at least 16°C, or 13°C where much of the work involves rigorous physical effort. These are important benchmarks, but they are not a universal pass-or-fail test. A cold store, hot process or temporary loss of heating still requires a suitable risk assessment and effective controls.
The absence of a statutory maximum does not mean high temperatures can be ignored. Heat is a workplace hazard. Employers must assess the risk, act on their findings and introduce temporary or seasonal controls where necessary.
HSE: workplace temperature and the law ↗ · Workplace Regulations 1992: regulation 7 ↗
Assess more than the number on the thermometer
Start with the work as it is actually done. Record the temperature, but also consider humidity, air movement, radiant heat, direct sunlight, cold surfaces and whether the task takes place indoors, outdoors or between different environments. A single reading taken beside a door or heater may not represent the worker's exposure.
Work rate matters because physical effort generates body heat. Clothing and PPE can restrict sweat evaporation, while gloves or bulky cold-weather clothing may reduce dexterity. Exposure duration, access to warm or cool rest areas, drinking water, shift timing and the opportunity to recover all affect the risk.
Speak with workers and supervisors. Reports of headaches, dizziness, muscle cramps, loss of concentration, numbness, shivering or difficulty using tools are evidence to investigate—not complaints to dismiss because a legal maximum has not been reached.
Related guide: getting risk assessments into the workplace →
Control heat at source before relying on resilience
Remove or reduce the heat source where reasonably practicable. Review the process, insulate hot plant and pipework, provide effective ventilation or cooling, and use barriers against radiant heat. Shade windows and outdoor work areas, move workstations away from direct sunlight and schedule demanding work for cooler periods.
Then adjust the system of work. Reduce the work rate, use mechanical aids, rotate people and provide planned recovery in a cooler area. Make cool drinking water readily available and encourage frequent small drinks. Waiting for someone to feel thirsty is not a reliable control against dehydration.
PPE must still protect against the hazard for which it was selected. Do not encourage workers to loosen respiratory, chemical or other protective equipment to cool down. Instead, reduce exposure time, provide longer recovery, review whether lighter suitable PPE is available and consider whether the process can be enclosed, automated or otherwise changed.
HSE: heat stress assessment and controls ↗ · Related guide: work at height risk assessment →
Turn heat and cold concerns into a workable control plan.
HR + SAFETY can review the workplace, task, PPE, welfare arrangements and vulnerable-worker factors, then set proportionate controls and clear escalation points for managers.
Discuss a temperature risk assessmentControl cold, draughts and changing conditions
For cold indoor work, provide adequate heating where possible, reduce draughts without compromising ventilation and limit contact with cold products or floors. Suitable clothing, footwear and gloves may be needed, but they should not create another risk by restricting movement, grip, hearing or visibility.
Outdoor workers may need warm and dry welfare facilities, more frequent breaks, suitable weather protection and work rescheduled around severe conditions. Consider wind chill, rain and wet clothing as well as air temperature. Driving, machinery use and work at height may become less reliable when workers are cold, fatigued or have reduced dexterity.
A local heater can create fire, electrical or fume risks if it is unsuitable, damaged or poorly positioned. Treat temporary heating as work equipment: select it for the environment, keep it away from combustible materials, inspect it and incorporate any changed fire hazards into the workplace fire risk assessment and emergency arrangements.
HSE: managing workplace temperature ↗ · Related guide: workplace fire evacuation planning →
Protect people who may be more vulnerable
Risk is not identical for every worker. Age, experience, pregnancy, disability, heart or respiratory conditions, medication and previous heat illness can affect tolerance. New starters and young workers may also be less familiar with symptoms or reluctant to stop and report a problem.
Use proportionate individual discussion and, where needed, occupational health advice. Possible measures include different work timing, closer supervision, reduced exposure, additional recovery, ready access to medication or fluids and a clear escalation plan. Keep medical information confidential while giving supervisors enough information to apply the agreed controls.
Heat stroke can involve confusion, convulsions and loss of consciousness and can be fatal. The assessment should state how workers summon help, who gives first aid, when emergency services are required and how a lone or remote worker will be monitored.
Related service: occupational health referrals → · Related guide: young worker risk assessment →
Workplace temperature assessment checklist
For offices and light work, a short documented review may be enough. Hot processes, cold stores, outdoor work, heavy physical tasks and restrictive PPE may need a more detailed assessment, monitoring plan and competent occupational-health input. Legal duties and HSE guidance were checked on 19 September 2026.
- Record representative temperatures across the work area and shift—not one convenient reading.
- Assess humidity, airflow, radiant heat, sunlight, wind, wet conditions and contact with hot or cold surfaces.
- Consider work rate, exposure duration, clothing, PPE and access to drinking water and recovery areas.
- Identify people who may be more susceptible and agree proportionate individual controls.
- Prioritise process, engineering and workplace controls before relying on rotation, breaks or PPE.
- Set clear triggers for extra controls, stopping work and escalating symptoms; do not rely on one universal temperature.
- Train workers and supervisors to recognise heat stress, dehydration and cold-related warning signs.
- Review welfare, first-aid, lone-working and emergency arrangements for the conditions expected.
- Record complaints, symptoms, equipment failures and weather events, then use them to review the assessment.
- Reassess after process, building, PPE, staffing or seasonal changes and after any temperature-related incident.
There is no single number that makes every workplace safe or unsafe. Use the 16°C and 13°C indoor benchmarks properly, assess the real thermal load and introduce controls that match the task, environment, PPE and people exposed.
This guide provides general information for UK employers. It is not legal advice and should not replace advice based on the facts of a specific matter.