Severe Heat Warning UK: What Your Employer Must Legally Do When Temperatures Soar

The Met Office issued an amber extreme heat warning on 20 June 2026, covering six English regions — East Midlands, West Midlands, South East, South West, East of England, and London — taking effect from Monday 22 June. A yellow heat-health alert is in place for Yorkshire and Humber, the North West, and the North East. By 11am on Monday, every region in England will be under at least some level of official heat-health alert, according to the UK Health Security Agency (UKHSA).

Temperatures are expected to test the all-time June record of 35.6°C. High overnight temperatures combined with elevated humidity will compound health risks, particularly for vulnerable groups. But amid the forecast headlines, one question matters urgently for millions of people heading into the office, warehouse, or construction site this week: what is your employer actually required to do — by law — when a severe heat warning is in force?

The Legal Gap Most Workers Don't Know About

Unlike many European countries, the UK has no fixed maximum workplace temperature written into law. The Workplace (Health, Safety and Welfare) Regulations 1992 require employers to maintain a "reasonable" temperature indoors during working hours, but the legislation deliberately leaves the threshold undefined.

The law specifies a minimum — indoor workplaces must not fall below 16°C (or 13°C for strenuous physical work) — but no numerical ceiling exists in statute.

That legal gap has been a source of growing controversy. The British Safety Council renewed calls in 2026 for a statutory maximum temperature for both indoor and outdoor work as June temperatures climbed toward record territory. The Climate Change Committee has separately urged ministers to act.

Until Parliament legislates, however, "reasonable" remains the operative word — and what it means in a heatwave is where employment lawyers earn their fees.

What the Law Actually Requires

The Health and Safety at Work etc. Act 1974 creates a broad duty of care for all employers. Under this legislation, employers must protect employees from all foreseeable harm, including heat stress. During an amber heat warning period, that duty is directly engaged.

According to Acas, the UK's statutory employment advice body, employers should take concrete steps when temperatures become uncomfortable or dangerous, including:

• Carrying out a thermal comfort risk assessment
• Providing cool rest areas and adjusting work schedules to avoid peak heat
• Offering regular breaks and access to cold drinking water
• Relaxing dress codes where appropriate
• Enabling remote working for office-based staff where heat cannot be controlled on-site
• Making specific provisions for pregnant workers, older employees, and those with existing medical conditions

The HSE (Health and Safety Executive) additionally requires that risk assessments specifically consider strenuous work and vulnerable staff — categories that expand significantly during an amber alert, when normally low-risk employees can become high-risk within hours.

When Can You Legally Refuse to Work?

This is the question most workers get wrong. Under Section 44 of the Employment Rights Act 1996, employees have the right to leave or refuse to attend a workplace if they reasonably believe there is a serious and imminent danger to their health. Extreme heat can, in principle, meet that threshold.

Proving it in practice is more difficult. Employment tribunals examine the reasonableness of the employee's belief, the nature of the work, the protections the employer had in place, and critically, whether the employee formally raised concerns before walking out. Acting unilaterally on personal discomfort — without first flagging the issue to a manager — significantly weakens any subsequent claim.

Employment solicitors consistently advise the same sequence: raise the issue in writing, document the employer's response, and seek legal advice before taking any unilateral action. This precedent applies across a range of crisis scenarios; the UK Terrorism Alert Raised to Severe: 5 Things Every Worker Should Know About Employer Duty of Care article illustrates how the same legal framework operates under different emergency conditions.

What "Reasonable" Looks Like in Practice

During a severe amber heat alert, a reasonable employer response goes well beyond opening a window. Employment lawyers look for these practical markers:

Office workers: Air conditioning, fans, or the option to work from home when indoor temperatures exceed 25–26°C. Cold water availability and scheduling intensive work for cooler morning hours.

Outdoor and construction workers: Mandatory shaded rest breaks, sunscreen provision, rescheduling heavy physical tasks away from peak sun hours (11am–3pm), and active monitoring for signs of heat stroke among crews.

Warehouse and factory workers: Industrial fans, dedicated cool rest rooms, adjusted shift patterns, and floor temperature monitoring — warehouses can regularly run 5–8°C hotter than external air temperatures during a heatwave.

If an employer has implemented none of these measures during an amber alert week and an employee suffers heat-related illness as a result, the legal exposure is real. The HSE can investigate and issue improvement notices; in serious cases, prosecutions under the Health and Safety at Work Act are possible.

Five Steps to Protect Yourself Legally This Week

With amber alerts active across England from Monday 22 June, here is how to act if your workplace is not responding adequately:

1. Email your manager now asking what heat risk measures are in place — digital communication creates an evidenced trail that a verbal question does not
2. Check your employment contract and health and safety policy for any temperature-specific provisions; some industries have sector-level agreements that go beyond the statutory minimum
3. Record indoor temperatures using a basic thermometer or smartphone app, noting timestamps — this documentation becomes evidence if you later need to make a complaint
4. Raise concerns formally with HR before taking any unilateral action such as leaving the premises or refusing to attend
5. Consult an employment solicitor if your employer fails to respond and you experience heat-related symptoms — free initial consultations are standard, and many workplace heat claims can be assessed quickly

The UK's absence of a legal temperature ceiling means individual circumstances carry enormous weight. What is reasonable in an air-conditioned law firm in Canary Wharf is not reasonable on a south-facing roof in July. Getting case-specific advice from a qualified employment lawyer is the only reliable route to understanding where you stand before an amber alert becomes a personal health crisis.

This article provides general legal information only and does not constitute legal advice. Individual circumstances vary. For advice specific to your situation, consult a qualified employment solicitor.