Heat rules in Western Australia: no set temperature, a duty under the WHS Act 2020 and WorkSafe's heat guidance

This page reports what the official source says. It is not legal advice: ask the office named here. It restates two WorkSafe Western Australia (WorkSafe) pages, "Working safely in hot conditions" and "Sun safety in the workplace", and the Bureau of Meteorology page on thermal comfort observations, all as read on October 9, 2026. Australian work health and safety law is state law, so the other states are covered on the Australia heat page and in the heat rules overview.

No stop-work temperature on the pages read

Neither WorkSafe page gives a temperature at which outdoor work must change or stop. The hot conditions page, last updated February 11, 2025, says the Work Health and Safety Act 2020 requires the employer or person conducting a business or undertaking (PCBU) to provide and maintain a working environment in which workers are not exposed to hazards or risks to their health and safety. It says this covers illness from working in heat. It also says both the Work Health and Safety (General) Regulations 2022 and the Work Health and Safety (Mines) Regulations 2022 require a supply of clean drinking water that workers can readily reach.

What the hot conditions page lists

Topic	What WorkSafe says
Where heat comes from	Hot climatic conditions, heavy work in moderately hot conditions, hot work processes such as welding or foundries, radiant heat, heavy protective clothing, or any mix of these
Risk factors to consider	Air temperature, humidity, radiant heat, air movement, workload, the worker's fitness, acclimatisation and health conditions, and clothing that limits sweat evaporation
Who is at greater risk	People who are medically unfit, on certain medications, overweight, with heart disease, pregnant, who abuse alcohol, or who are not acclimatised
Acclimatisation	Takes 7 to 14 days to take effect, can reduce after 3 days away from hot work, and is entirely lost after 4 weeks away
Fluids	A supply of clean drinking water that workers can readily reach
Consultation	PCBUs consult workers likely to be exposed to heat, and any elected health and safety representatives, when identifying, assessing and controlling the risk

Forms of heat illness it names

The page separates four stages. Discomfort covers flushed skin, more sweating and heat rash. Mild heat illness covers tiredness, weakness, dizziness, cramps, shorter attention span and irritability. Heat exhaustion covers fainting, headache, low blood pressure, nausea and clammy, pale or flushed skin, with a body temperature that is normal to high, up to 39 degrees Celsius. Heat stroke covers confusion, speech problems, hot dry skin, convulsions and unconsciousness, with a body temperature above 40 degrees Celsius. The page calls heat stroke potentially fatal and life-threatening.

Assessing and controlling the risk

WorkSafe says the risk assessment is carried out by a person competent in heat assessment and may use a heat stress index. It names the Wet Bulb Globe Temperature (WBGT) as a commonly used index, and the Thermal Work Limit (TWL) as an alternative used increasingly in Australian workplaces, particularly in the resource industry. It lists the order of controls as engineering (fans, shade cloth, shields, air conditioning), organisation of work (hot tasks in the cooler part of the day, task rotation, more workers, extra rest breaks in cool shaded areas, mechanical aids), training and information (with toolbox and pre-start meetings as the way to reinforce it) and protective clothing.

What the Bureau of Meteorology says about WBGT

The Bureau's thermal comfort page says human comfort depends on four environmental factors, which are wind, air temperature, humidity and radiation from the sun and hot surfaces, plus clothing and activity level. It says high humidity significantly reduces the cooling from sweat evaporation. It says the WBGT was developed in the late 1950s for the US Marine Corps Recruit Depot on Parris Island, and that standard ISO 7243 recommends it, so it is often used in occupational health and safety guidelines. The Bureau adds that the WBGT it publishes is only an approximation that ignores variations in wind and radiation, and that wind and radiation are best measured on location. The WorkSafe page itself points to the Bureau for WBGT values for major centres.

Sun safety page

The sun safety page, last updated November 25, 2024, was produced by Cancer Council WA with WorkSafe. It says the UV Index at 3 and above is strong enough to damage skin, that the Bureau issues a SunSmart UV Alert when the index is forecast to reach 3 or above, and that UV peaks between 10.00 am and 3.00 pm. It says heat and UV are not related, so UV can be very high on a cool or cloudy day.