When does the season end proper and the frostbite season begin?
Obviously the sea breeze is not there as per summer (what sea breeze i hear you ask) so what is the average wind strength of a usual, sailable day out during winter. What kind of gear would i be looking at rigging. 
I realize this is a generalized question so i expect generalized answers 
the season never ends, windsurfing is an all year sport for perth, about four years ago i remember quite a windy summer, (used 4.7m ALOT) and during the winter the westerly fronts would come one after the other for about 4-5 days with 25knot plus winds super consistent as well, there were times during winter where we sailed about 4 times a week, was great
You can still get an april seabreeze, and this week looks OK for acouple of sessions.
Winter is better toward the end so it is not really on until July in an average year.
Winter can still be a front per week, meaning a good sail - just that the wind may be in the middle of the night sometimes 
As to the size to rig, that is hard to say as the wind picks up then drops off. So depends on your timing - you can have an awesome sesh in a NNW pre-frontal on say 5.5 - 6.0 with sunny skies, and nukin' 4.0 weather and rain only 4 hrs later
After the westerly starts to swing WSW then SW it will drop radically so I reckon the best sailing is just prior to the front arrival as it will build during your session, then you pack up juussst before the rain and stuff
very.....
