What the Law Says About Working in a Heatwave

Your office feels like an oven, the fan in the corner is doing nothing, and you have started to wonder whether your boss can legally make you sit there and sweat through another spreadsheet. So at what point can you down tools and go home?

The short answer might surprise you.

As another mini-heatwave settles in, with amber heat alerts in place across the country and temperatures expected to reach 34°C in London this week, health and safety experts at High Speed Training have set out what the law actually says about working in the heat, and what your employer is supposed to do about it.

Is there really no maximum temperature?

Here is the bit that catches a lot of people out. There is no legal maximum working temperature in the UK. None. You cannot point at a thermometer hitting a magic number and walk out the door.

What the law does say is that working temperatures must provide “reasonable comfort,” according to the Health and Safety Executive (HSE). It is an employer’s legal duty to carry out a risk assessment to work out a suitable temperature for their particular environment, taking into account factors like humidity, airflow, and physical effort.

In other words, an office job and a job hauling stock around a warm warehouse are not judged by the same standard.

Why the heat is more than just uncomfortable

Working through a heatwave is not only unpleasant, it can be genuinely dangerous in certain jobs, and it drags down productivity across the board. Excessive heat can lead to poor concentration, reduced productivity, and heat stress, which becomes a significant safety risk in safety-critical roles.

Dr Richard Anderson, Head of Learning and Development at High Speed Training, said working through high temperatures can be hard going, particularly where there is no proper air conditioning.

“Working in the middle of a heatwave can be incredibly uncomfortable, especially in buildings or environments where adequate air conditioning isn’t available,” Richard said.

What your employer can do

The good news is that there is plenty an employer can do short of sending everyone home. Following a risk assessment, the measures they might take include:

• Installing and maintaining air conditioning units where possible, though this is not always reasonably practicable
• Relaxing the dress code, so no ties or suit jackets if a suit is the norm
• Providing refreshments. Fresh drinking water is a legal requirement, but ice and squash can help further
• Providing desk fans or temporary cooling units to improve air circulation
• Moving desks out of direct sunlight to cooler spots
• Installing curtains and blinds on sun-facing windows
• Allowing flexible hours so staff can work earlier or later when it is cooler
• Relaxing attendance rules to allow working from home where that is more comfortable

Employers are also expected to take extra care of anyone more vulnerable to the heat. Hot weather can leave people feeling tired and sluggish, and that hits young and elderly people, pregnant women, and those on certain medication harder than most. Extra rest breaks or a desk fan can make a real difference.

What if you work from home?

For the growing number of people working from home, the responsibility can feel a bit blurry. Whose job is it to keep you cool in your own spare room?

Richard said the duty still sits with the employer.

“For those working from home on a temporary or permanent basis, the lines may appear to be blurred between who is responsible for what. But it’s important to note that employers have a duty to ensure the health and safety of all their employees, regardless of where they work.”

That means employers should help home workers keep a comfortable temperature, whether by providing fans, allowing flexible working, or offering guidance on staying cool. Richard suggested practical steps such as keeping curtains closed in sun-facing rooms and taking plenty of breaks to drink water and regain concentration.

And if none of that is enough?

“If employees working from home still struggle with heat after these considerations, further measures may need to be discussed as part of the risk assessment,” Richard said. “For example, determining if there is a local office that is air-conditioned or generally cooler than their home where they can temporarily work.”

Further advice is available on the HSE website, which includes guidance on heat stress.