This is interesting.
I found live temperature readouts from Bathurst Airport which is not too far from Wiruna:
http://www.bom.gov.au/products/IDN60...01.94729.shtml
Looks like it got down to only about 11°C last night, although it was a little colder the night before at 9°C. It's currently sitting around the 12°C at the moment.
I assume these should be fairly similar temperatures to what we'll see in a weeks time.