Construction · Heat
The maximum temperature is only the start.
A single maximum temperature hides when the heat occurs and how the work is organised. Use the forecast to start a site discussion about exposure and the task.
Read the hours the crew will work
Open the hourly explorer for the correct place. Compare temperature across the shift and note available humidity and wind information. Check official warnings separately, and record the forecast time so an updated view is not confused with the earlier plan.
Do not interpret a feels-like temperature as a workplace heat-stress assessment or a UV measurement.
Review the task as well as the forecast
Safe Work Australia’s heat guide covers work-related heat risks. Factors such as workload, protective clothing and the work environment belong in the assessment alongside weather. Follow the site’s heat-management arrangements and use the official guide for controls and illness-response information.
This page does not prescribe a universal stop-work temperature. A cooler forecast number alone is not approval to resume a task.
There is no single stop-work temperature
Safe Work Australia answers this directly. Asked whether there is a maximum temperature at which workers must stop work, its answer is no: a single stop-work temperature cannot account for all the factors that make working in heat hazardous. Instead, the business or undertaking must eliminate or minimise the risk so far as is reasonably practicable. Its guidance gives cancelling outdoor work when temperatures are high as one example of eliminating the hazard.
Site agreements, enterprise agreements or company policies may set their own triggers. Those come from the site’s documents, not from a weather app.
What the guidance asks you to consider
Safe Work Australia’s guide lists the factors to consider when identifying heat as a hazard: air temperature, air flow, humidity, radiant heat sources, the work requirements, the workers and the workplace. It notes that radiant heat can be high in the sun, especially on a concrete or metal roof, that high humidity makes it harder to cool down, and that clothing and PPE can stop sweat evaporating.
It also describes heatwaves, when the maximum and minimum temperatures are unusually hot over at least three days. Warmer nights reduce sleep quality, high temperatures arrive earlier and last longer, and fatigue builds. A forecast run of hot days and warm nights is therefore worth planning for as a block, not one shift at a time.
Apparent temperature, humidity and UV
Apparent temperature. Safe Work Australia mentions apparent temperature, calculated from air temperature and relative humidity, as a simple index for estimating how hot conditions feel. The feels-like figure in Atmosphr comes from Open-Meteo, which describes it as combining wind chill, relative humidity and solar radiation. It is a model estimate for the forecast point, not a measurement of heat stress on your site.
Humidity. Check the hourly relative humidity beside the temperature. A moderate temperature with high humidity can be harder work than a drier, hotter hour.
UV. Heat and ultraviolet radiation are separate hazards. Cancer Council Australia explains that the UV Index runs from low (1 to 2) and moderate (3 to 5) to high (6 to 7), very high (8 to 10) and extreme (11 and above). The Bureau issues sun protection times when the UV Index is forecast to reach 3 or above, and Cancer Council advises the five SunSmart steps whenever it is 3 or above, including on cool or cloudy days. Atmosphr shows an hourly model UV Index; ARPANSA publishes measured UV for its monitoring sites.
Planning questions for a hot shift
These questions are adapted from the risk management checklist in Safe Work Australia’s guide. The forecast helps with some of them; the rest need people on site.
| Question | Where the forecast helps | What it cannot tell you |
|---|---|---|
| Are conditions hot, and when? | Hourly temperature and apparent temperature across the shift | Radiant heat on a roof deck or near plant |
| Are days and nights hotter than usual? | Several days of maximum and minimum temperatures | How well the crew slept |
| Is it humid? | Hourly relative humidity | Humidity inside enclosed work areas |
| Is there air movement? | Forecast wind at 10 metres | Air flow in a trench, roof cavity or confined space |
| When is the work done? | Which hours are coolest | Whether the task can actually move |
| How often can workers rest somewhere cool? | Nothing directly | Shade, cooling and water on site |
| Are workers fit and acclimatised, and what are they wearing? | Nothing | Workload, PPE and individual health |
Record the answers with the forecast time. If the day turns out hotter than forecast, the plan should already say who reviews it.
Other official tools worth knowing
Safe Work Australia’s guide points to the Bureau of Meteorology’s Heatwave Service, which forecasts the location and severity of heatwaves, and to a basic heat stress calculator published by Workplace Health and Safety Queensland. For complex situations it suggests engaging an occupational hygienist.
Its first aid fact sheet stresses that heat-related illness is progressive: if a worker is not treated or stays in a hot environment, it can be fatal. Make sure the site knows who the first aiders are, where the cool rest area is and how to get help, before the hottest hours arrive.
A clear pre-start note
Record the expected work period, the forecast source, who is reviewing the site conditions and when the next check is due. Include the site’s agreed plan for changing the task or timing if conditions require it.
Use the planning checklist. For a pour, also read the concreting weather guide: worker exposure and concrete placement are separate checks.