What temperature is too hot to work under UK law? Heatwave to bring 40C weather to London

Tuesday is forecast to be a scorcher with temperatures edging 36C, but Wednesday will be the peak of the heatwave as the mercury hits 40C.

The rest of the week will be cooler, but temperatures will still sit between 27C and 29C through the weekend.

The same can be said for many of London’s office buildings, which lack the architectural design to keep cool when the mercury soars.

While more modern buildings will likely come equipped with temperature regulators, many other workers may have to crack open a window.

Luckily, Brits have some rights regarding workplace protections, meaning your boss has to be mindful of office temperatures. The workplace temperature rules in the indoor workplace are covered by the Workplace (Health, Safety and Welfare) Regulations 1992.

But there’s a bit of a catch. Here’s what you need to know about your employee rights when it gets too hot.

The regulations state that employers must legally provide employees with a “reasonable” temperature in the workplace and good ventilation.

But legally, there is no minimum temperature or statutory upper limit for workplaces, meaning employers actually rely on workplace recommendations rather than law.

The Approved Code of Practice says that the lowest recommended temperature is 16ºC, or 13ºC when it’s physical work, but there’s no such guidance for the other end of the spectrum.

Due to the high temperatures found in certain work environments such as glass or foundries, no meaningful figure has been determined for when it is too hot to work.

The Health and Safety Executive (HSE) said: “In such environments, it is possible to work safely provided appropriate controls are present.”

The Chartered Institute of Building Service Engineers recommends the following temperatures for different working conditions:

According to the Government website, “Employees should talk to their employer if the workplace temperature is not comfortable.”

The HSE says: “If a significant number of employees are complaining about thermal discomfort, your employer should carry out a risk assessment, and act on the results of that assessment.”

HSE guidelines also advise that employers should make sure their workers have access to water during hot weather.

So while you can certainly complain to your employer if the temperature is making you feel uncomfortable, it doesn’t necessarily mean you can go home.

In June 2024, the Trades Union Congress warned that the government must bring in maximum working temperatures. It said that continuing to work in hot weather can lead to dehydration, rashes, fainting and – in extreme cases – loss of consciousness. It added that outdoor workers are three times more likely to develop skin cancer.

According to the HSE, an acceptable thermal comfort for most people lies roughly between 13C and 30C.

But there are currently no official plans to introduce a maximum working temperature by law.

Just like the UK, some European countries have guidelines and recommendations about when it gets too hot in the office. For example, there appears to be a work limit if office temperatures rise above 27°C in Spain, while countries like France and Germany don’t have a defined upper limit but do have strict workplace protections.

What’s more, some European countries are much more accustomed to dealing with a scorching summer.

From offices in the European mainland equipped with air conditioning to some nations encouraging afternoon siestas, our European neighbours may seem more equipped to handle the heat.

In Spain, for example, it’s also very common for businesses to take the month of August off when temperatures reach their peak.