A Maximum Working Temperature Could Be on the Table. What’s Already on Yours Is a Legal Duty.

Another surge of hot weather has come and gone in the UK, and once again the conversation has turned to whether the UK should set a legal maximum working temperature. The Climate Change Committee added its voice in May, recommending the government commit to one as part of its A Well-Adapted UK report. The unions have wanted it for years. And every August, when the temperature climbs, someone asks me the same question: “Is it illegal to make people work in this?”

The honest answer comes as a shocking surprise for many. No, there is no legal maximum. However, that isn’t the same as saying employers have no responsibility. I have spent the best part of four decades watching employers wait for a number that was never coming, when the duty was sitting in front of them the whole time.

Why Is There No Maximum Working Temperature in the UK?

There is a legal minimum — the Approved Code of Practice to the Workplace (Health, Safety and Welfare) Regulations 1992 sets it at 16°C, or 13°C for strenuous physical work. There is no equivalent upper figure, and that catches people out. The reasoning is practical rather than negligent: a commercial bakery, a foundry and an open-plan office are not the same thermal environment, and a single statutory ceiling would be unworkable across all of them.

Instead, the Regulations require that indoor temperature be “reasonable”, and that employers maintain what the guidance calls thermal comfort. The word “reasonable” does a lot of heavy lifting in that sentence.

What Does the Law Actually Require When It Gets Hot?

Your duty does not switch on at a particular temperature. It runs all year through the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations 1999, which require you to assess and control foreseeable risks. Heat is a foreseeable risk — demonstrably so, given that last year was the UK's warmest on record and we recorded the hottest May day ever this year. Treating a heatwave as a surprise is no longer a defence I would want to stand behind.

There is a sharper edge to this too. Under Section 44 of the Employment Rights Act 1996, a worker can withdraw from a situation they reasonably believe presents serious and imminent danger, without detriment. That threshold is quite high — it covers danger, not general discomfort — but heat stress in the wrong setting can absolutely cross it. I would much rather an employer manage the risk down than discover where that line sits in a tribunal.

Should You Wait for a Legal Limit Before Acting?

No, and I would gently point out that the proposed figures don't even agree with each other. The GMB has long campaigned for 25°C. Usdaw and others point to 30°C, or 27°C for strenuous work. The World Health Organization references 24°C as a comfortable ceiling. The HSE, meanwhile, is developing hot-weather guidance but is expected to stop short of a hard legal maximum.

For us as practitioners, the exact number matters far less than having a plan that triggers before you reach it. A good heat policy doesn't ask “have we broken a limit?” It asks “what are we doing at 24°C, and what changes at 27°C?” That is risk assessment doing its job, and it is entirely within your gift today.

What Should Health and Safety Professionals Do Before Next Summer?

The mistake is to start thinking about when summer rolls around. The work belongs in the cooler months, when you can plan rather than react. A few practical priorities:

• Use the HSE thermal comfort checklist to establish whether you have a genuine risk, then record a proper heat risk assessment rather than relying on memory of “what we did last time”.
• Write a written hot-weather policy with clear trigger points — relaxed dress codes, rotated tasks, adjusted start times, mandatory rest and rehydration — rather than leaving each summer to improvisation.
• Pay particular attention to outdoor and process workers, who face the highest exposure and the longest UV risk, and to anyone with a health condition that affects heat tolerance.
• Treat cooling as an engineering control, not a perk. Ventilation, shading and air conditioning are the kind of investment the Climate Change Committee is trying to incentivise, and they protect productivity as well as people.

None of that requires a new law. It requires the same systematic approach we apply to every other foreseeable hazard.

Frequently Asked Questions

Is There a Legal Maximum Working Temperature in the UK?

No. There is no statutory maximum. The law requires indoor workplace temperatures to be “reasonable” and employers to manage heat as a foreseeable risk under existing health and safety legislation.

Can Employees Refuse to Work Because It's Too Hot?

In limited circumstances. Section 44 of the Employment Rights Act 1996 protects a worker who withdraws from serious and imminent danger. This is a high threshold and covers risk such as heat stress, not ordinary discomfort.

What Temperature Are the Unions Asking For?

Proposals vary: the GMB has campaigned for 25°C, while others have proposed 30°C, or 27°C for strenuous work. The Climate Change Committee recommended a maximum in principle without fixing a single figure.

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