Heat stress and working in heat: the signs, the rules and how to roster a hot day

Heat stress is when the body can’t shed heat fast enough to hold its core temperature near 37°C. Left unchecked it becomes heat-related illness, from cramps and heat exhaustion through to heat stroke, a medical emergency. Australia sets no maximum temperature for work. The duty is to manage the risk, and the roster is a big part of that.

That definition is WorkSafe Queensland’s. This is general information, not medical, legal or safety advice.

What heat stress does to the body

Safe Work Australia’s working in heat FAQ lists heat exhaustion, heat cramp, dehydration, fainting and heat stroke, and says heat-related illness is progressive and “can be life threatening if left untreated”. Most at risk, on the same page: young (under 25) and older workers, pregnant women, people with physical illness such as heart disease, and workers who aren’t acclimatised.

The signs below come from healthdirect and Safe Work Australia’s first aid page for heat-related illness. Not every sign appears every time.

While the ambulance comes, Safe Work Australia’s first aid is to cool the person fast: cold water immersion from the neck down where practicable, otherwise wet skin, moving air and cold packs, with fluids only if fully conscious. That’s a planning summary, not first aid training.

One sign in that table should change how you roster: confusion. The person with heat stroke is the one least able to notice it.

WorkSafe Queensland also describes a “heat hangover” after repeated moderate exposure: irritability, headaches, nausea, loss of appetite and lethargy late in the shift or the next one.

Is there a maximum temperature for work in Australia?

No. Safe Work Australia’s FAQ says a single stop-work temperature “can’t account for all the factors that make working in heat hazardous”: humidity, air flow, how hard and how long people work, and whether they’re fit and acclimatised.

What exists is the general duty. A PCBU must eliminate or minimise the risk so far as is reasonably practicable, which Safe Work Australia says “may include cancelling or rescheduling certain work tasks until conditions are cooler”. It must also consult affected workers and provide first aid, trained first aiders included. Workers must take reasonable care of their own safety.

Triggers can still exist. SafeWork NSW notes that when a business consults its workers and HSRs, “agreement may be reached on specific parameters” for when work stops in extreme heat, and those go in the workplace heat management plan. Enterprise agreements and principal contractors’ site rules may set their own. Check the ones covering each crew, and run the day to the strictest. A trained HSR can also direct a worker to cease unsafe work where there’s a serious risk from an immediate or imminent hazard.

What drives heat risk on site

The factors below are from Safe Work Australia’s heat risk checklist and WorkSafe Queensland, and the last column is ours.

Controls, from the top of the hierarchy down

Safe Work Australia’s hierarchy for heat, with SafeWork NSW’s examples:

• Eliminate. Cancel outdoor work when temperatures are high, or do it at another time or place.
• Substitute. Give the physical work to a machine.
• Isolate. Separate workers from hot plant, or start on the shady side of the building and follow the shade around it.
• Engineering. Shade structures, fans, air conditioning, air-conditioned cabins in plant.
• Administrative. Training, supervision, and scheduling demanding work into cooler parts of the day.
• PPE. Light, breathable clothing and hats. SafeWork NSW warns that PPE can add heat load, and that admin controls and PPE should only back up higher ones.

Moving tomorrow’s pour to 5am is scheduling. Moving it to a cooler day is close to elimination. An esky of water at the gate is a good thing, and it isn’t a heat plan.

Rostering for heat: where most of the controls live

SafeWork NSW’s administrative controls read like a rostering brief: shorter shifts, more rotation, cooler hours, new workers eased in, and first aiders who know heat illness on all shifts. Each is decided the week or afternoon before, so a heat plan that lives only in the toolbox talk arrives too late.

Start earlier and finish before the peak

WorkSafe Queensland suggests night, early morning or late afternoon rather than midday. Start earlier, do the pour and the hand digging first, and give the afternoon the shaded, lighter tasks or send the crew home.

It has costs. An earlier start takes sleep and shortens the break since yesterday’s finish, and awards and agreements may set spans of hours and minimum breaks. A 5am start with an hour’s drive is a 3:45am alarm. Check the maximum hours you can work in a row, and don’t claw the hours back with a 12-hour shift on the next cool day.

Shorter shifts, more breaks, slower pace

SafeWork NSW lists breaks in cool or air-conditioned areas, work paced to the conditions and shorter shifts. The roster consequence is arithmetic: the same work at a slower pace needs more people or more days. A program that assumes June output in February will be late in February.

Rotate between sun and shade

Pair a sun task with a shade task and swap at each break. Rotation fails quietly on tickets. If one person holds the EWP ticket, that person is on the boom all day. Two ticket holders per hot task is what makes rotation real.

Acclimatisation for new starters and anyone coming back

Safe Work Australia says workers who aren’t acclimatised, or are “returning after being away for a week or more”, are at higher risk. It also says not to rely on acclimatisation as a control, and to set up programs with a professional such as an occupational hygienist. SafeWork NSW: ease new workers in gradually, with extra breaks and a slowly rising workload.

That catches more than new starters: Monday’s labour hire crew, the leading hand back from three weeks’ leave, and on a 2/1 swing roster, everyone coming back from a week off. Put them on the lighter, shaded work first, next to someone who’s been in the heat all month.

Buddy checks, first aiders and lone work

In a heatwave Safe Work Australia says workers shouldn’t work alone where possible, and anyone who must should be monitored and able to get help. WorkSafe Queensland and SafeWork NSW both list a buddy system.

The buddy catches what self-assessment can’t. On a forecast hot day, pair names on the roster, and give any lone shift a buddy or a tighter check-in schedule (the lone worker check-in procedure covers the rest). Then check the first aider, because moving the crew to 5am can leave them on the 7am roster.

FIFO and remote sites

Distance stretches the gap between collapse and ambulance, so cooling first aid carries more of the load. The drive in and out belongs on a journey management plan on a hot day too, because a breakdown with no shade is a heat problem before it is a mechanical one. WorkSafe Queensland says that where heat stroke is a risk, the emergency plan needs heat stroke procedures and workers trained to run them, which means a first aider and cooling gear on every hot shift.

The Bureau of Meteorology notes that hot nights make it harder to recover from the heat of the day, and a FIFO worker who slept badly in a hot room starts behind.

Night work: cooler, with a cost

Nights are on WorkSafe Queensland’s list, and for some tasks they’re right. They also swap a heat problem for a fatigue one, because day sleep in a hot house during a heatwave is poor sleep. If work goes to night shift, run it as a block under the night rules in your fatigue management plan, not a crew flipped overnight with no rest between.

How a forecast changes tomorrow’s roster

The Bureau of Meteorology’s heatwave service warns of severe or extreme heatwaves within the next 4 days and forecasts likely heatwaves 7 days out. Warnings are issued at 3pm local time (2pm in WA), generally October to the end of March. A heatwave is a run of 3 unusually hot days and nights for that location, so day three deserves a different plan from day one.

Move the week’s heavy tasks on Monday. Check mid-afternoon each day, apply the policy trigger, rebuild tomorrow and tell the crew at pack-up. A change decided at 8pm is contact outside working hours, and under the right to disconnect a worker can decline to read it unless that’s unreasonable. Then check who has seen it, and ring the rest while it’s still light.

What to put in a hot weather policy

SafeWork NSW recommends a heat management plan written with workers and their HSRs. A hot weather policy a supervisor can run from needs:

1. Scope. Employees, labour hire and subcontractors, which sites, and any stricter client rule.
2. Who watches the conditions. The role that monitors heat and forecasts, and the time each day the call is made.
3. Triggers and levels. What forecast or reading moves the site to which controls, plus any agreed stop-work parameters.
4. Controls at each level. Start times, heavy tasks first, breaks, rotation, water and shade.
5. Acclimatisation. How new starters and anyone back after a week or more are eased in.
6. Buddies and lone work. The pairing rule on hot days and the check-in schedule for anyone alone.
7. Clothing and PPE. What comes off on breaks and what’s worn underneath.
8. First aid and emergencies. The signs, calling 000 for suspected heat stroke, a first aider on every shift, cooling gear and the remote evacuation plan.
9. Stopping work. How anyone raises a concern, the HSR’s role, and no penalty for stopping.
10. Telling the crew. The channel, the cut-off time and who checks it was seen.
11. Records and review. Decisions, roster changes and incidents, reviewed after any heat illness and before each summer.

The heat toolbox talk carries it to the crew, and the fit for work declaration can carry the hot-day questions.

Where Humanz fits

Humanz doesn’t read the forecast, measure temperature or decide when it’s too hot to work. It holds the roster, where these decisions land.

When a shift is updated the worker gets a push notification, and the Show Unseen filter narrows the schedule to shifts nobody has opened, so the 5am start that hasn’t landed shows up at 3pm, not at the gate. Broadcast notifications reach everyone on a job at once, and job messages keep read receipts and a retained history.

Fatigue rules check hours and rest as each shift is placed, so an early start that breaks minimum rest is flagged before it’s confirmed. Tickets, first aid certificates among them, sit on each worker’s profile with expiry alerts. A start-of-shift form from the custom form builder can carry the hot-day questions, completed offline and timestamped against the job.

Humanz does not track location, use AI, calculate pay or interpret awards, or give medical or safety advice. If your hot-day changes go out by group text at 8pm, see them in rostering software with a record behind them, and book a walkthrough before the first heatwave.

Frequently asked questions

What is heat stress?

Heat stress is when the body cannot cool itself fast enough to keep its core temperature at a safe level of around 37°C, as WorkSafe Queensland defines it. It depends on the environment (air temperature, humidity, radiant heat, air movement), the work (intensity, duration, clothing and PPE) and the person (acclimatisation, fitness, hydration, health, medications). Left unmanaged it leads to heat-related illness, from heat cramps and heat exhaustion through to heat stroke.

Is there a maximum temperature for working outside in Australia?

No. Safe Work Australia says there is no maximum temperature at which workers must stop work, because one number cannot account for humidity, air flow, workload and acclimatisation. The duty is to eliminate or minimise the risk, which can mean rescheduling work until it is cooler. Some enterprise agreements, site rules and agreed workplace heat plans set their own stop-work triggers, and those still apply.

What are the first signs of heat stress at work?

Early signs include thirst, sweating, muscle cramps, headache, dizziness, nausea, slower thinking and visual disturbances. Because confusion is a sign of heat stroke, workers in the heat should check on each other rather than rely on spotting the signs in themselves.

What is the difference between heat exhaustion and heat stroke?

Heat exhaustion is a serious illness with thirst, weakness or cramps, headache, dizziness or fainting, and a normal or raised body temperature. Heat stroke is a life-threatening emergency in which body temperature rises sharply and the brain is affected, causing confusion, poor coordination, slurred speech, seizures or collapse. Heat exhaustion can become heat stroke, and Safe Work Australia says to call an ambulance immediately if you suspect either.

What should you do if someone has heat stroke at work?

Call 000 for an ambulance immediately, then start cooling the person while you wait. Safe Work Australia’s first aid guidance is to move them somewhere cool with moving air, lie them flat, remove unnecessary clothing including PPE, and immerse the body from the neck down in cold water for 15 minutes where practicable. If that is not possible, wet the skin, fan air over them, put cold packs at the neck, groin and armpits, and give fluids only if they are fully conscious.

How do you roster crews for hot weather?

Start earlier so heavy work is done before the hottest part of the day, shorten shifts or add cool breaks, and rotate workers between sun and shade. Ease new starters and anyone back after a week or more away in gradually, pair workers up, and keep a trained first aider on every shift. Decide in the afternoon and tell the crew before they knock off.

What should a hot weather policy include?

A hot weather policy should cover its scope, who monitors conditions, triggers and the controls at each level, acclimatisation, buddy and lone work rules, clothing and PPE, the emergency response, stopping work without penalty, how roster changes are communicated, and records and review. Write it with workers and their health and safety representatives.