The direction of the long RWY [03-21] is not too bad from the terrain perspective, but the airport really needs the 06-24 cross runway as well for the strong morning easterlies and strong afternoon westerlies. The terrain advantage of 03-21 is that the approaches are over flat land, whereas 06-24 points at the Perth Hills.
The wind roses below show the pattern. The dark brown colour - not doubt chosen by the meteorologist to represent the pucker factor - are winds in excess of 30 kph (16.7 knots); the length of the dark brown is proportional to the percent of time that it is at that strength and direction.
3pm summer is not too bad, but 9am/3pm winter and 9am summer show why the cross-wind on 03-21 can be a problem.
