This article is from the Storms FAQ, by Chris Landsea firstname.lastname@example.org with numerous contributions by others.
The Australian forecasters have developed a scale for tropical
cyclone intensity for storms in their area of responsibility - 90 to 160E
(Holland 1993). Note that the sustained winds are based upon a 10 min
averaging period instead of the USA 1 minute period.
Australian Scale Sustained Winds (km/hr) 1 63-90 km/hr 2 91-125 3 126-165 4 166-225 5 > 225