Yep, it's winter in August. Not sure the seasons always know when they're meant to end to be prepared for it still to be cold
Coming from Europe I haven't found it too cold here. It's rare it snows in Wellington (very rare) were as I'm used to snow every year.
I don't remember a frost last year in Wellington...but that could still be my rose-tinted glasses
Coming from a warmer climate you're going to feel it!
Buy some thermal layers. You'll need a hat and scarf and good rain jacket if you're coming to Wellington.
When the sun is out it can still be warm and it still warms up my house as I'm in a sunny site - but in the shade it's cold. So it's important to find a house on the sunny side of a hill to keep your electricity bills down!
Wellington is a great place - look us up (WNN) when you arrive!