The United Kingdom enjoys nothing more than talking about the weather and in 2018 there has been much to discuss. Over the past few months, the country has gone from shivering in sub-zero temperatures to experiencing one of the hottest summers on record.

Although the sun may be more welcome than the snow, it can still cause headaches for employers. This update outlines the factors that they should keep in mind when the mercury starts rising.

Working indoors

While health and safety laws do not specify maximum and minimum workplace temperatures, they do stipulate that the temperature inside buildings should be reasonable during working hours.

There is no legal definition of 'reasonable' and this will depend to some extent on what workers are doing, with more active tasks requiring a cooler temperature. The Health and Safety Executive (HSE) code of practice suggests a minimum of 16 degrees Celsius (or 13 degrees Celsius if the work is particularly physical), but provides no maximum temperature. However, for most kinds of work, the acceptable range lies between 16 and 24 degrees Celsius.

The HSE's guidance advises employers to focus on their workers' "thermal comfort" (ie, their perception of temperature and the effect that it has on them) when regulating workplace temperatures. According to the HSE, those experiencing thermal discomfort will make more mistakes and operate more dangerously in the workplace.

The HSE sets out the following factors that determine the level of thermal comfort experienced by workers:

  • environmental factors:
    • air temperature;
    • radiant temperature (ie, the presence of hot objects);
    • air velocity; and
    • humidity; and
  • personal factors:
    • clothing insulation; and
    • metabolic heat (ie, the heat that individuals naturally produce).

The HSE has published a thermal comfort checklist that can help employers to identify issues. Although not intended as a proper risk assessment, more than two ticks indicate that there may be a problem with heat in the workplace.

In hot weather, employers should consider steps to achieve a more comfortable environment, such as:

  • using air conditioning units or fans;
  • shading windows; and
  • increasing ventilation.

Employers could also consider relaxing dress codes in order for employees to stay cooler.

Working outdoors

For those who work outdoors or in an environment without air conditioning, work can become particularly exhausting in hot weather. Heat and dehydration detrimentally affect decision making and physical ability, while heavy sweating can make the working experience uncomfortable and unpleasant.

If possible, work should be rescheduled to cooler times of the day or longer and more frequent breaks should be allowed, with somewhere shady to rest. To keep employees happy and productive, they should have access to sufficient water to remain fully hydrated throughout the working day.

Employers should ensure that workers have appropriate clothing to protect them from the sun (eg, hats and long-sleeved tops). In addition, skin cancer is the fifth most common cancer in the United Kingdom; therefore, employers should ensure that all employees working outside have access to sunscreen with a high-protection factor.


Temperatures exceeding 27 degrees Celsius can cause steel railway tracks to swell and buckle. Speed restrictions become necessary to minimise stress to the line and enable drivers to identify warped tracks and stop in time. In addition, with roads melting in the heat, drivers can also face delays.

As such, absences and lateness become more common during a heatwave. Unless strict punctuality is crucial, employers should consider a more relaxed approach to delays.

If workers fail to attend work for a reason outside their control (eg, heat-related travel disruptions), they may not be legally entitled to payment. However, employers should be cautious about docking workers' pay. Not only is this likely to have a negative effect on employees' morale, but it could also give rise to adverse publicity.

Guidance from the Advisory, Conciliation and Arbitration Service advocates a flexible approach in such situations, stating: "The handling of bad weather and travel disruption can be an opportunity for an employer to enhance staff morale and productivity by the way it is handled."

Walking on sunshine

Sunny days make many people feel more cheerful and fine weather may provide an opportunity for some impromptu and low-cost employee bonding. Employers may decide to spend some of their social budget on organised fun, such as a lunchtime picnic or post-work softball game. After all, the opportunity may not last.

For further information on this topic please contact Bethan Carney or Tom Heys at Lewis Silkin by telephone (+44 20 7074 8000?) or email ( or The Lewis Silkin website can be accessed at

This article was first published by the International Law Office, a premium online legal update service for major companies and law firms worldwide. Register for a free subscription.