Grapes in Late May?

The co driver came home the other day with a bag of white table grapes from the supermarket.
Grapes in May I thought? That’s very late in the year.
They were branded Autumn King.
So I did a bit of investigation.
Autumn King is a late-season white seedless table grape developed by David Ramming and Ronald Tarailo of the USDA-ARS in Parlier, California.
The cultivar, formerly known as C10, was released in 2006 and resulted from the cross of USDA selections A61-20 x B99-131. The parentage of Autumn King is complex and includes Agadia, Blackrose, Calmeria, Cardinal, Divizich Early, Italia, Maraville, Muscat Hamburg, Muscat of Alexandria, Perlette, Sultanina and Tafafihi Ahmur.
The only informative video I could find was American.
Check out the size of the bunches and the high trellising system.  

The cultivar produces medium-sized (0.5 kg), conical to cylindrical- shaped bunches that are medium to well filled. The natural berry size of Autumn King is quite large and without gibberellin or girdling, berry weight can average 8-9 grams or more. Berries are cylindrical to ovoid in shape, and have medium to firm flesh and skin. The berries contain 2-3 aborted seeds which are inconspicuous when eaten and the flavor is described as sweet and neutral.
Autumn King ripens mid-September through to November or about eight weeks after Thompson Seedless, the predominant white table grape.
That’s the USA seasonal range; delete 6 months (or add) for us down under.
There are four licensed Autumn King grape growers in Australia, all in North Western Victoria.