Don’t think because its blue skies and no clouds in Perth that the same will be in the Avon Valley. Just get some cool temps, no breeze and a little low lying waters and you can very easily find yourself in fog just as I did. I was inspired by the day then all of a sudden it was like a blanket came down and there was this thick fog around. It took until midday to start to burn off but then the day was glorious.
One thing I didn't expect to see was a guy galloping up the footpath... I felt like I was back in Texas. Passing traffic seemed to take note and slow a little so as not to startle the horse.