As the UK swelters under a heatwave that has seen the Met Office issue its highest-level warnings, the modest office thermostat has suddenly become a hot topic in more ways than one. What might once have been a mild grumble about stuffy meeting rooms is now a genuine workplace issue, with employees wilting at their desks and employers wondering where their legal obligations stretch.

Employer obligations on workplace temperature in the UK

UK employment law does not set a prescribed maximum workplace temperature for office environments. Instead, the Health and Safety at Work etc. Act 1974 and the Workplace (Health, Safety and Welfare) Regulations 1992 require employers to maintain a “reasonable workplace temperature”. This may sound rather vague, and, arguably, this was the intention so as to get employers to think about their particular circumstances. What is reasonable at 9 am on a breezy spring morning may feel very different at 3 pm during a heatwave, particularly when the current overnight “tropical” temperatures offer little chance to cool down.

What is a ‘reasonable’ working temperature?

In practice, this means employers need to keep a close eye on conditions and be prepared to act when things start to overheat, sometimes literally. The Health and Safety Executive promotes a common-sense, risk-based approach. Employers should consider workplace ventilation, humidity, and the nature of the work employees are required to undertake, as these factors can influence how temperature affects their employees. Steps should be taken to reduce discomfort and risk. That might mean providing fans, loosening the dress code (ties, be gone), adjusting working hours, or even embracing the increasingly popular solution of home working when the office starts to feel like a greenhouse.

Legal risks of failing to act

Importantly, when dealing with very hot (or cold) weather, it is not just about comfort but also legal risk. Temperature-related complaints can feed into broader employment claims and workplace dissatisfaction. Persistent inaction could contribute to poor performance, attendance issues, grievances, constructive dismissal arguments, or even personal injury claims if employees suffer heat-related illness. And for those with underlying health conditions, the Equality Act 2010 may apply, requiring reasonable adjustments such as relocating to cooler areas or making more flexible working arrangements.

Preparing for future extreme weather events

What makes this particularly relevant now is that heatwaves are predicted to become more common. Climate data suggests that extreme temperatures are becoming more frequent, with 40°C days now far more likely than in previous decades, and projections indicate hotter, longer summers ahead. In other words, the occasional scorching day in the office may soon become a regular feature of working life.

So, how can responsible employers ensure they are meeting their obligations during extreme weather? As with most issues, it pays to be prepared. At Lester Aldridge, we are advising our clients to get ahead of potential employment issues relating to weather conditions by investing in equipment to stave off the worst of the heat (think fans and air-conditioning units), carrying out extreme weather risk assessments, and adopting a broader “weather event” policy for employers covering a range of extremes, such as heatwaves, heavy snow and flooding. Having these frameworks in place can take much of the uncertainty (and debate) out of decisions made during disruptive weather and can reduce the likelihood of employee disputes when it’s too hot to keep calm and carry on.

After all, you cannot control the British weather, but you can control how prepared you are when it inevitably turns up the heat, and how effectively you meet your employment law and health and safety obligations as an employer.