No Maximum Work Temperature? 5 Heatwave Myths, Busted

The bit no one tells you about heatwaves at work

Every year, the first proper hot week lands and three things happen at once.

• One: someone asks if they can go home because it is too hot to work and thinks it is the law.
• Two: someone else turns up in flip-flops and a vest, and a customer notices.
• Three: your inbox fills with newsletters about heatwaves at work that contradict each other.

So here is the part most of them skip.

There is no maximum workplace temperature in UK law.

There is no number on a thermometer that forces you to down tools. Those 30 degrees and 27 degrees figures are TUC campaign asks, not law. Never have been.

What you do have is a legal duty of care. The Health and Safety at Work etc. Act 1974 says you must keep people safe so far as is reasonably practicable. The Workplace (Health, Safety and Welfare) Regulations 1992 say temperature must be reasonable. The Approved Code of Practice gives a minimum for cold conditions, but still no maximum.

Reasonable is the keyword. Reasonable in a glass office at 32 degrees is not the same as reasonable on a roof at 32 degrees. Reasonable for a fit 25-year-old is not the same as reasonable for a 58-year-old on blood pressure medication or someone who is 30 weeks pregnant.

You do not have a number to hide behind. You have a judgement to make.

Kettle on. Cold tap, this time.

Heatwaves at work: the legal lowdown

Let us get the law straight in 30 seconds.

• There is no legal maximum workplace temperature.
• Employers must keep the working environment at a reasonable temperature.
• You must assess risk and act, particularly for higher-risk workers.

ACAS puts it simply:

> "There is no law for minimum or maximum working temperatures, for example when it is too cold or too hot to work." (ACAS, Temperature at work)

Links to read and save:

• ACAS: Temperature at work
• HSE: Temperature at work
• HSWA 1974, Section 2
• Workplace (Health, Safety and Welfare) Regulations 1992, Regulation 7

A quick reality check. The Met Office confirmed the UK exceeded 40 C for the first time in 2022. That heat is not theoretical any more. Source: Met Office record heat summary.

Why this hits small businesses hard

Big firms have facilities teams, HR, air con contracts, and a policy.

You have a £6 thermometer if you remembered to buy one, a desk fan from 2019, and a chat thread full of people saying it is boiling.

Every person matters more. If two of your six people are out with heat exhaustion on Wednesday, that is a third of your team gone for days. If someone collapses on site, you are the one calling the ambulance, their partner, and your insurer.

The legal and financial hit is real. A heat-related personal injury claim, plus legal fees and lost time, can run into five figures. Add HSE attention and Working Time Regulations issues about rest in hot conditions and it drags on for months.

You do not need convincing this matters. You need a simple method.

Myths to bin before the mercury rises

1: It is the law to send people home at 30 degrees

It is not. There is no legal maximum. You can send people home if your risk assessment says that is reasonable. It is your call, not an automatic right.

2: No air con means there is nothing I can do

You have plenty. Fans, blinds down, hydration stations, flexible hours, relaxed dress code, longer breaks, remote work where it helps, earlier starts. Most are low cost.

3: Everyone is the same in the heat

They are not. Pregnant workers, people with cardiovascular or respiratory conditions, people on some medications, older workers, and new arrivals to the UK may struggle sooner. The Equality Act 2010 means one size fits all is not good enough. Pregnant workers need a written risk assessment. Use ACAS guidance and HSE templates:

• ACAS: Pregnancy and maternity health and safety
• HSE: New and expectant mothers

4: If they wore shorts, that is their problem

Dress code is your policy. If it makes heat risk worse, relax it and tell people clearly what is acceptable. Vagueness leads to complaints.

5: Working from home fixes the heat

Sometimes. Some homes are cooler. Others are top-floor ovens. Remote work is one tool, not the answer by itself.

Your hot-weather plan: 5 practical steps

Get these in place before or at the start of a hot spell and you will be in a strong, defensible position.

1. Take the temperature and record it

Buy a cheap digital thermometer. Take readings mid-morning and mid-afternoon in the actual work area. Log them, three a day. It proves you checked and helps you decide.

2. Write a one-page hot weather note

Email it and pin it up. Keep it short and clear. Include:

• Temporary dress code relaxation, spelled out in plain terms
• Water available and frequent drink breaks encouraged
• Flex to start and finish earlier where possible
• Individual adjustments for anyone who needs them, including pregnancy and health conditions
• What to do if someone feels unwell: stop, cool, drink, tell a manager
• Flex on finish times for long, hot commutes

Two minutes to read. Twenty minutes to write.

3. Identify higher-risk people discreetly

Think through your team. Who is pregnant? Who has asthma, heart conditions, diabetes, or takes heat-sensitive medication? Who is over 60? Who is new to UK summers? Who works outdoors, in vehicles, kitchens, or low airflow spaces? Have a quiet, individual chat and agree adjustments. For pregnant workers, complete and file a written risk assessment.

4. Move the work around

Heat peaks roughly 11am to 4pm. Shift demanding work outside that window where you can.

• Builders: start earlier
• Drivers: longest routes in the morning
• Offices: heavy screen work in the morning, meetings later or shorter
• Kitchens: prep early, minimum heat at peak, second prep after 4pm

Treat it like a snow day. What would you move to keep people safe and the wheels turning?

5. Spot early signs and act

• Heat exhaustion: headache, dizziness, heavy sweating, cramps, feeling sick, very thirsty, fast pulse. Fix with rest, shade, water, time.
• Heat stroke: confusion, no sweating despite heat, very high temperature, fainting, unresponsive. Call 999. Cool while waiting. Do not give water if they are not fully alert.

Model the behaviour. Say out loud: I am grabbing water and ten minutes in the cooler room. Back shortly. That permission matters.

Extra care for higher risk work

Construction, roofing, outdoor trades

UV, dehydration, and height risks stack. Water in every vehicle. Sunscreen on site. Start times pulled earlier. Read HSE's outdoor heat guidance:

• HSE: Working in hot environments

Kitchens, bakeries, laundries, manufacturing

Ambient heat is already high. Extractors on full. Doors propped where safe. Rotate people through the hottest spots. Offer electrolyte drinks as well as water.

Delivery drivers, couriers, mobile workers

Cabs without air con heat fast. More breaks, more water, adjust route expectations. Do not chase normal timings at 35 degrees in a van.

Care, healthcare, and customer-facing retail

Indoors can be hot too. Big windows and older buildings trap heat. Residents and customers matter, and so do your team.

When the heat arrives: quick answers and a seven minute plan

Two questions you will get

• Can I work from home for the week? Answer: Maybe. If the work can be done as well from home and the home is cooler and safer, yes. Decide case by case.
• Why are we here if the school sent children home? Answer: Schools have different safeguarding duties. Acknowledge it is hot, explain what you are doing, and offer the flex you can.

The seven minute action list

1. Find or buy a thermometer. Take a reading. Log it.

2. Email a four-line note: dress code relaxed (be specific), water available, breaks flexible, tell us if you are struggling.

3. Quietly message the two or three people most at risk. Check in today.

4. Move one heavy or outdoor task out of 11am to 4pm.

5. If anyone is pregnant, complete a short hot-weather risk note today.

6. Write down this rule: we would rather lose an hour than spend half a day in A and E. Then follow it.

7. Book a 15 minute review after the hot spell. Keep what worked. Fix what did not.

As the Met Office now records 40 C heat in the UK, plan for hot weeks as a normal risk, not a surprise.

As we wrap up, remember this: compliance is good, compassion is better. Keep it human and fair.

Need help putting this in place

• Book a free HR Health Check: Book a free HR Health Check
• Want to talk through your team and workplace setup: Book a discovery call
• On the go: Listen to the Buzzing About HR podcast: Buzzing About HR

Keep buzzing and take care of your people.

Frequently asked questions

• Is there a maximum temperature for workplaces in the UK

No. There is no legal maximum. Employers must keep temperature reasonable and manage risk. See ACAS and HSE links above.

• Can staff refuse to work if it is too hot

They can raise a genuine health and safety concern. You must assess and act. If risk is serious and you fail to act, employees have protection for leaving a dangerous workplace.

• Do pregnant workers need special steps in hot weather

Yes. Complete a written risk assessment and adjust duties, hours, and environment as needed. Use ACAS guidance and HSE templates.

• What are the signs of heat exhaustion and heat stroke

Exhaustion: heavy sweating, cramps, headache, dizziness. Stroke: confusion, no sweating, very high temperature, collapse. Stop work and follow the steps above. Call 999 for heat stroke.

• Do I have to pay people sent home due to heat

If you choose to stop work, normal pay usually applies unless your contracts say otherwise. Avoid deductions that risk unlawful deduction claims. Seek advice before changing pay.

• Does air conditioning change my obligations

No. You still need to assess risk, monitor, and make adjustments for higher-risk staff. Air con helps but does not remove your duty of care.