Read the gusts as well as the wind.

Three checks before comparing a limit

1. Units: keep km/h, m/s and knots distinct. If a limit uses another unit, convert both values to the same unit before comparing them.
2. Quantity: determine whether the plan refers to a gust or an average wind speed. Do not compare unlike measurements.
3. Location: identify the forecast point and the position where wind is measured on site. A model grid value is not a reading at a crane jib or an exposed edge.

Who sets the operating limit?

SafeWork NSW says there is no single wind speed that makes every construction activity unsafe. Its guidance points to site assessments, plant limits and clear stop-work triggers. Confirm the applicable manufacturer instructions and site plan with the responsible person.

Atmosphr does not calculate a safe lifting window. Use the hourly forecast to identify periods needing attention and the official guidance to inform the site’s review.

Convert the units before you compare

Atmosphr shows wind in km/h. Equipment plates and manuals often use metres per second, and marine and aviation products use knots. The conversions are exact: 1 m/s is 3.6 km/h, and 1 knot is 1.852 km/h (one nautical mile per hour).

To convert km/h to m/s, divide by 3.6. To convert km/h to knots, divide by 1.852. Values in the table are rounded to one decimal place.

Average wind and gusts are different numbers

The Bureau of Meteorology explains that forecast wind speed is an average over 10 minutes, measured at 10 metres above the surface. Gusts are short bursts, usually lasting a few seconds, and within any 10-minute period they can be 40% stronger than the average. Its example: an average of 25 knots (about 46 km/h) can come with gusts of 35 knots (about 65 km/h).

Atmosphr’s hourly figures come from Open-Meteo. Its documentation describes wind speed at 10 metres as the standard level, given as a value for the indicated hour, and the gust figure as the maximum gust at 10 metres during the preceding hour. The Elevating Work Platform Association of Australia (EWPA) also warns that wind speed changes can be up to 50% of the average in gusty conditions.

So check both columns. A modest average with a high gust figure describes a very different hour from a steady wind.

Wind is usually stronger at height

Friction slows wind near the ground, so wind at the surface is usually lighter than the 10 metre value, and wind higher up is usually stronger. The EWPA’s good practice guide says wind may be 50% faster 20 metres above the ground and can be amplified around buildings by funnelling. SafeWork NSW notes that on construction sites wind is often stronger at height and more dangerous around open structures, unfinished buildings, exposed edges and temporary works.

A forecast for 10 metres is not the wind at a crane jib, the top of a scaffold or a platform raised beside a building. That is why site guidance points to measuring wind where the work happens, with an anemometer, rather than judging it by eye.

Equipment limits come from the manufacturer

For mobile elevating work platforms, the EWPA guide says only machines rated for a wind speed of at least 12.5 m/s (45 km/h) should be used outdoors. The rating is marked on the manufacturer’s serial plate and on a decal on the platform, and the machine must not be operated outside it. Some machines are rated for indoor use only, so 12.5 m/s is a minimum for outdoor use, not a universal safe limit.

SafeWork NSW lists what to settle before work starts: check forecasts, review the site risk assessment and safe work method statements, confirm the wind limits for cranes, elevating work platforms and other plant, check wind loading for scaffolds and temporary works, and set clear stop-work triggers. During work it says to stop plant, crane and lifting operations when manufacturer limits are reached. Crane limits, and any limit for a particular load, come from the crane’s own documentation and the lift plan.

A worked example

Suppose the hourly forecast for a site shows an average of 25 km/h with gusts to 45 km/h at 10 metres, and the platform on site is rated at 12.5 m/s. Converting, 12.5 m/s is 45 km/h, so the forecast gust at 10 metres already equals the rating, and the platform will be working higher than that.

This does not produce a go or no-go answer. It tells the supervisor that the hour needs an on-site reading at working height, a check of the machine’s own limits and the site’s agreed triggers, and a plan for what happens if the wind rises. Record the forecast time, the measured values and the decision.

Before the site is left unattended

Check the overnight and weekend wind as well as the working hours. SafeWork NSW lists steps for making an unattended site safe before severe weather: clear debris, block access to elevated areas, scaffolds and ladders, secure plant and equipment, store tools and hazardous materials, cover pits and trenches, and display after-hours contact details. It also warns against sheltering behind incomplete masonry walls in extreme weather, even when temporary supports are in place. For warnings, use the Bureau rather than a model map.

Make the handover specific

For example, record “wind and gust forecast reviewed for the delivery and unloading period; site monitoring and equipment limit checked by the supervisor.” Add the actual source time and local measurements. This is more useful than writing “windy today”.

Open the printable planning checklist or compare hourly wind and gusts.

Sources and further reading

• SafeWork NSW: high winds in construction
• BOM: wind, gusts and squalls
• EWPA: Mobile Elevating Work Platform Good Practice Guide v2.0 (PDF)
• Open-Meteo forecast API documentation