-15 is beyond my comprehension. My experience is limited to a couple below zero at worst. OTOH I have always assumed that people who live in the cold have the buildings and the heating and the clothes that are appropriate for it.

The Riverina region is largely dead flat. There are outcrops (eg the massive rock called The Rock, also another one called Galore Hill) and areas of small hills. Lots of flooding and very fertile. Beautiful countryside, yes.