UK temperatures climbed above 30°C during the June 2026 heatwave, and 1 in 10 workers say they would consider quitting over office temperatures. That figure translates to roughly 3 million people across offices, warehouses, food factories and construction sites running the same quiet calculation: how long can I keep showing up to a workplace that feels genuinely unsafe?

The structural problem behind that number is well-established but underappreciated. The UK has no statutory maximum workplace temperature. The Health and Safety Executive (HSE) publishes guidance on thermal comfort and cites 16°C as a minimum for sedentary indoor work under the Workplace (Health, Safety and Welfare) Regulations 1992, but sets no upper ceiling. The primary duty sits in the Health and Safety at Work etc. Act 1974, which requires employers to ensure, so far as is reasonably practicable, the health, safety and welfare of their workers. The Management of Health and Safety at Work Regulations 1999 add a specific obligation to conduct suitable and sufficient risk assessments for all significant hazards, and extreme heat qualifies. A red heat-health alert issued by the UK Health Security Agency counts as a workplace health and safety event, triggering those assessment duties in practice, even though no single temperature number is written into statute. That ambiguity is precisely where friction between workers and employers is building.

What the data is actually saying

The 1-in-10 figure is the headline finding, but the sectoral texture underneath it matters more. Food factory workers in Yorkshire regularly experience workplace temperatures in the high 30s°C. Construction workers face dehydration, heatstroke and serious injury risk during red alerts. Economists are now warning that sustained extreme heat disruption will dent European economic growth, which means the cost surfaces in productivity data and output figures, not merely in resignation letters.

Three things are happening simultaneously: workers are reaching a personal threshold faster than employers are building policy to meet them; HR teams are improvising responses on the day of each red alert rather than executing pre-written plans; and unions including Unite the Union and the Trades Union Congress (TUC) are treating heat events as a live bargaining anchor, pressing for heat breaks, paid stand-down provisions and remote-work entitlements in collective agreements. None of that dynamic goes away when the temperature falls back to 22°C in July.

For employees: what you can actually ask for

If you are working in a building that hits the high 20s indoors and your concentration is gone by early afternoon, you are responding to a real workplace condition, not being unreasonable. Your employer carries a duty under the Health and Safety at Work etc. Act 1974 to manage conditions that affect your health and safety, and that duty does not disappear because no magic upper number is written into the regulations. The HSE's own thermal comfort guidance makes clear that temperatures high enough to cause discomfort, distraction or heat-related illness must be assessed and controlled.

Practical requests that tend to land well, particularly on red-alert days:

• A temporary remote-work window on the hottest days, even for roles that are normally on-site. Framing the request as a productivity question rather than a personal preference makes it easier for your line manager to action.
• Adjusted hours: an earlier start so your shift or working day ends before the afternoon peak. This sits comfortably within what ACAS (the Advisory, Conciliation and Arbitration Service) describes as a reasonable adjustment under a flexible working request.
• Scheduled heat breaks with access to drinking water and a cooler rest space, particularly relevant for workers in food manufacturing, logistics, warehousing or outdoor roles.
• A written risk assessment for your specific role and environment. Under the Management of Health and Safety at Work Regulations 1999, your employer should be able to produce one for hot-weather conditions. If they cannot, that absence is itself a data point worth noting.

Before escalating a grievance or considering resignation, it is worth checking what other employers in your sector actually do during heat events, not what their job adverts say. The CIPD (Chartered Institute of Personnel and Development) has consistently found that workplace culture signals, including how a company behaves when physical conditions get difficult, are among the strongest predictors of longer-term retention. Employer reviews from people who have worked through previous heatwaves at a given company carry more signal than any job description.

For HR and employers: the legal exposure is quieter than you think

The absence of a statutory maximum temperature is not a shield. It is, in practice, the opposite. Without a clear number on the statute book, every red-alert day becomes a case-by-case judgement call, and case-by-case judgement is exactly the territory in which health and safety claims, formal grievances and constructive dismissal arguments take root. Under section 44 of the Employment Rights Act 1996, a worker who reasonably believes they face serious and imminent danger at work has the right to leave or refuse to return without being subjected to any detriment. That provision does not require a breach of a specific temperature threshold. It requires a reasonable belief, and 38°C in a poorly ventilated food production unit is a credible foundation for that belief.

HR action plan guidance for the heatwave, authored by Emma O'Connor, identifies three controllable levers: risk assessments under the 1999 Management Regulations, reasonable adjustments for affected workers, and flexible working protocols. None of those levers require a change in primary legislation. All of them require a written policy that exists before the next alert, not improvised during it.

The retention calculation

If 10% of your workforce is prepared to consider leaving over temperature, the cost of replacing even a fraction of them outweighs the cost of a drafted heat-event policy by a considerable margin. Recruitment cycles in food manufacturing, logistics and warehousing are already stretched by structural vacancy pressure. Heat-driven attrition lands on top of that existing strain, not instead of it. The CIPD's annual Reward Management Survey data consistently shows that workplace environment and physical safety perceptions rank as primary retention factors among shift-based and manual roles. Treating heat policy as a retention investment, rather than a welfare gesture, changes how you resource it and how you communicate it to line managers.

The union signal

Unite the Union and the TUC have both signalled that heat events are becoming a formal bargaining anchor: heat breaks, paid stand-down on red-alert days, and remote-work entitlements are among the provisions being sought in workplace agreements. Under section 188 of the Trade Union and Labour Relations (Consolidation) Act 1992 (TULRCA 1992), collective consultation obligations apply when significant changes to working conditions affect 20 or more employees. An employer who waits for union pressure before drafting a heat policy will be negotiating under time pressure and under a legal framework that requires advance consultation. The order of operations matters significantly here.

What a defensible heat policy actually contains

A workable heat policy is not a lengthy document. It is a short one that answers four questions with specificity:

• Trigger: the condition that activates the policy, for example a red heat-health alert from the UK Health Security Agency, or an internally measured temperature threshold for specific sites such as production floors or warehouses.
• Adjustments: remote-work eligibility criteria, shift-time changes, mandated breaks, hydration access, and cooling provision (fans, air conditioning, shading for outdoor workers).
• Accountability: who is responsible for confirming the trigger has been met, and how quickly that decision is communicated to line managers and shift supervisors.
• Pay treatment: what happens to pay if a site is stood down or hours are reduced, particularly for shift workers, zero-hours staff and outdoor crews.

The pay treatment clause is the one most policies omit and the one most disputes turn on. The HSE's own enforcement guidance and ACAS good-practice materials both flag pay clarity during stand-down events as a frequent source of grievance. Writing it down before the next alert, with a clear reference to the relevant contractual provisions, removes the most contentious ambiguity at the point of highest stress.

The bigger picture

Heatwaves are not a one-off event series. The June 2026 episode sits within a pattern that economists are now building into European growth forecasts. For workers, that means thermal conditions are going to remain a working-conditions question each summer, not an unusual weather complaint. For employers, it means the policies drafted this summer will face operational testing again next year, and the year after. The organisations that manage this well, across both the employee experience and the employer liability dimensions, are the ones that stop treating each heatwave as an administrative surprise requiring improvisation. The 1-in-10 figure is not a threat. It is a reading of where the threshold currently sits. The HSE's framework, ACAS's guidance and the growing union push from Unite and the TUC give both sides enough structure to act well before the next red alert is issued.