The most useful tool I've found for deciding if it's likely to be clear/cloudy on the day are near real-time hourly
satellite images from the Brisbane storm chasers. It's much higher resolution than the publicly-available BoM images, and with practice you can easily track weather systems, low and high cloud bands, fog or storms across Australia. The facility to animate the hourly images is incredibly handy, as is zooming in to state level (NSW 09:33am image attached).
Use the animations of visible light images during the day to track the progress/development of a weather system, bearing in mind things like patches of fast high clouds crossing a whole state in a few hours, much faster than a frontal system! You can use the IR images to track high cold clouds overnight, but the low clouds (e.g. fog, or Melbourne winter cloud off the ocean) don't show up well in night-time IR over land as they're near the same temperature as the ground.
Today looks very promising - keep an eye on the high cloud over the SA/NSW border in case it extends eastwards later on, but the front modelled in SkippySky as bringing a lot of cloud has already fizzled almost entirely
. If this continues, I'll hopefully head up to Katoomba for near sunset!
What's the form on departing late evening? I'm intending to leave maybe about 11pm, so I can get home and rested before a golf comp in the morning, but I don't want to disturb other observers!