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Wind Speed

Wind speed and direction must be taken into account before you start spraying. You need to ask yourself:

  • How fast is the wind blowing?
  • Is the wind blowing towards or away from sensitive areas?

You can measure wind speed with a hand-held anenometer. These are available from outdoor and boating retailers from between $75 - $250. Make sure you get a model that operates well at low wind speeds.

Alternatively, use the benchmarks in the following table to assess wind speed.

Wind speed guide
Approx. airspeed at nozzle height Description Visible signs Spraying
Less than 2 km/h Calm Smoke rises vertically Use only medium or coarse spray quality
2 - 3 km/h Light air Direction shown by smoke drift Avoid fine spray on warm, sunny days
3 - 6 km/h Light breeze Leaves rustle, wind felt on face Ideal spraying conditions
6 - 10 km/h Gentle breeze Leaves and twigs in constant motion Good spraying
10 - 15 km/h Moderate breeze Small branches move, raises dust or loose paper Increased risk of spray drift, avoid fine sprays
15-20 km/h Fresh breeze Small trees sway Extreme caution with any sprays
>20 km/h Strong breeze Large branches sway Unsuitable for spraying