A Geomagnetic Storm is happening NOW (10:00 pm AEST), it may produce auroras in Tasmania, Southern New Zealand and the Antarctic territories. Check http://www.ips.gov.au/Space_Weather for near real time updates and look towards the south to see if you can catch an aurora (from Tasmania you may see more of a reddish glow than sheets of light in the sky, you will also need to get your eyes to accommodate for around 5-10 minutes to be able to see any aurora).
This is the result of a Coronal Mass Ejection from the Sun on August 1. Some media outlets have been a little, shall we say, hysterical, but while it's the first decent CME for a while it's not particularly large. Anyway, look out for auroras.
UPDATE: 11:00 PM AEST. The K index is still up at 6, and the Solar wind velocity is still high, biyt no reports of aurora from anyone. Even if I could see aurora this far north, my Southern horizon is covered in cloud.
UPDATE 2: Looks like everywhere in AUstralia that could see aurora is covered in cloud. Meh!