UK heatwave: How hot does it have to be to legally leave work in the UK? Your rights explained

The Met Office has forecast that the mercury will reach highs of 29°C in Sussex on Tuesday (July 12), with hot temperatures forecast across the UK for the rest of the week.

And next week is predicted to be even hotter, with the Met Office forecasting temperatures of up to 35°C next Monday (July 18)

But how hot does it need to to be before it becomes too hot to work?

According to gov.uk, guidance suggests a minimum of 16ºC or 13ºC if employees are doing physical work but there’s no law for minimum or maximum working temperatures.

There’s no guidance for a maximum temperature limit. During working hours the temperature in all indoor workplaces must be reasonable.

Employers must stick to health and safety at work law, including:

- keeping the temperature at a comfortable level

- providing clean and fresh air

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Employees should talk to their employer if the workplace temperature isn’t comfortable.

The Heath and Safety Executive has previously issued a number of guidelines when it comes to working environment.

They have said that, during working hours, the temperature in all indoor workplaces must be reasonable.

However, there is no maximum temperature given due to high temperatures of working in some places, for example a glass works or foundry.

While 'reasonable' is rather ambiguous, the law does say that an employer must act if a 'significant number of employees are complaining about thermal discomfort'.

If this is the case then your employer should carry out a risk assessment. There are six basic factors an employee should look at including air temperature, radiant temperature (i.e., the temperature radiating from warm objects), air velocity, humidity, and what clothing or insulation workers are expected to wear.

A HSE spokesperson said: "As an employer you should be aware of these risks and make sure the underlying reasons for these unsafe behaviours are understood and actively discouraged and/or prevented.

"The more physical work we do, the more heat we produce. The more heat we produce, the more heat needs to be lost so we don’t overheat. The impact of metabolic rate on thermal comfort is critical."