News

24th June 2026

Working Safely in Hot Weather: Understanding the Risks and Responsibilities

Many people work outdoors or in environments where temperatures can rise significantly during the summer months. With the current heat wave, it’s important for employers and workers alike to understand how heat can affect health, safety and wellbeing, as well as the factors that contribute to high workplace temperatures.

Recent heatwaves have seen temperatures reach record-breaking levels, and while hot weather has traditionally been viewed as a temporary inconvenience, it is becoming an increasingly important workplace health and safety consideration.

What Affects Workplace Temperature?

Workplace temperature is influenced by more than just the weather forecast. Several factors can affect how hot employees feel and how effectively their bodies can cope with the conditions.

Air Temperature

The surrounding air temperature has the most obvious impact, particularly for those working outdoors or in buildings without adequate ventilation or cooling systems.

Radiant Heat

Heat can also be generated by nearby surfaces and equipment. Materials such as tarmac, roofing materials, machinery, engines, and even building façades can absorb and radiate heat, significantly increasing the temperature experienced by workers.

Humidity

Humidity plays a major role in how the body responds to heat. When humidity levels are high, sweat cannot evaporate effectively, making it harder for the body to cool itself and increasing the risk of heat-related illness.

Air Movement

Airflow helps remove heat from the body and improves the effectiveness of sweating. Low air movement can make hot conditions feel considerably more uncomfortable and dangerous.

 

How the Body Responds to Heat

The human body constantly works to maintain a core temperature of around 37°C. During hot weather, particularly when carrying out physical work, the body faces additional challenges.

Physical activity generates metabolic heat, causing the body’s temperature to rise. To compensate, the body increases blood flow to the skin and produces sweat to promote cooling through evaporation.

However, this process relies heavily on adequate hydration. Excessive sweating without sufficient fluid replacement can lead to dehydration, reducing the body’s ability to regulate temperature and increasing the risk of heat-related illness.

 

Understanding Heat Stress

Heat stress occurs when the body is unable to cool itself effectively. Early symptoms may include:

• Excessive sweating
• Fatigue
• Headaches
• Dizziness
• Muscle cramps
• Difficulty concentrating

If not addressed, heat stress can develop into heat exhaustion and, in severe cases, heat stroke — a medical emergency that requires immediate treatment.

Beyond the health implications, heat stress can impair judgement, concentration, and reaction times, increasing the likelihood of workplace accidents and errors.

 

The Importance of Wet Bulb Temperature

A term becoming increasingly relevant in occupational health and safety is Wet Bulb Temperature.

Unlike standard air temperature measurements, Wet Bulb Temperature takes both heat and humidity into account. It reflects how effectively sweat can evaporate from the skin and therefore how efficiently the body can cool itself.

When humidity is high, sweat remains on the skin rather than evaporating. Workers may continue losing fluids through sweating, but the cooling effect is significantly reduced.

This is why a humid 30°C day can often feel more uncomfortable and potentially more dangerous than a dry 35°C day.

Understanding the combined effects of temperature and humidity can help employers make more informed decisions about working practices during periods of extreme heat.

 

What Does the Law Say?

There is currently no maximum legal workplace temperature in the UK.

However, employers have a duty under the Health and Safety at Work etc. Act 1974 to provide, so far as is reasonably practicable, a safe working environment for employees.

This includes assessing risks associated with hot weather and implementing suitable control measures where necessary.

Employers should consider:

• Providing access to drinking water
• Encouraging regular hydration
• Scheduling physically demanding work for cooler parts of the day where possible
• Providing shaded or cooled rest areas
• Allowing more frequent breaks
• Monitoring workers for signs of heat-related illness
• Reviewing personal protective equipment requirements where appropriate

 

Practical Steps for Workers

Workers can also play an important role in managing heat-related risks by:

• Drinking water regularly throughout the day
• Wearing suitable lightweight clothing where work activities allow
• Taking breaks in shaded or cooler areas
• Reporting symptoms of heat stress early
• Looking out for colleagues who may be affected by the heat

 

Looking Ahead

Heatwaves are becoming more frequent and more intense, creating new challenges for employers and health and safety professionals. While there is no single solution, understanding the risks associated with heat exposure is the first step towards protecting workers and maintaining safe operations.

By assessing workplace conditions, planning ahead, and implementing sensible control measures, organisations can reduce the risks associated with hot weather and help ensure that people remain safe, healthy, and productive throughout the summer months.