Hi Joe, thanks for the kind feedback 🙂

As you’ve noticed, the southerlies aren’t really “true” ones, in the sense that they aren’t Antarctic or from the pole. The large and stubborn high pressure zone south of Australia has been encouraging a lot of west to south-west winds into NZ, often lately our ‘southerlies’ have been coming out of Tasmania area. So not super chilled. These highs are like eggs or rugby balls in shape, and they usually lie west to east. However, when they are shaped “tall” from north to south (like a rugby ball on the ground before you kick it) it can have much bigger ‘reach’ over the Southern Ocean and if there’s low pressure near Dunedin offshore to the South east those two systems can dredge up icy air from off the ice shelf. The last time NZ had that in a major way was August 2011 when it snowed in some parts of Auckland City, the Bombay Hills, Pukekohe and even on the hills of Northland going into the Far North. So two things are likely at play: 1) the shape of the current highs being west to east (rugby ball on its side) and 2) the warming of the planet is adding a degree or two to what we thought was a normal average 30 years ago.

Cheers
Phil D