Looking promising if we add a seabreeze on top of that prediction (not sure this site is that good a predicting local seabreezes?)
On the topic of getting equipment ready, it's really helpful in races if people have sail numbers organised. If your a member of Windsurfing SA, you already have an allocated national sail number.
I thought I'd share my "cheapskate" method for doing sail numbers. First, use your computer to print your numbers out on A4 sheets, one number per page as large as you can make it. Cut them out, and this is your template. Maybe stick them on thin cardboard for durability - you only need to make these templates once.
Go to your hardware store and get some adhesive vinyl (aka Contact) in black or whatever colour contrasts your sail. Don't scrimp and get cheaper Contact from a $2 store. Reverse the templates and trace the number outline on the back of the adhesive vinyl, then cut out the numbers.
Now, choose a part of your sail that does not have any seams in the way. A seam under the number is a weak spot that will allow water underneath. Clean the area of the sail with metho and a paper towel and allow to dry - a few minutes. Work the backing off one small corner of the number. Carefully stick the number to the sail by holding it in place and peeling off the backing from under the number, starting from the corner where the backing has already been peeled back. Keep the number flat, making sure it goes down with no wrinkles. What the heck, this bit is the same for all sail numbers anyway.
Now rub the number down with a semi-hard edge that won't damage the sail or number. I use the end of a plastic ruler. If you look underneath the number (on monofilm anyway) you can see where the adhesive has "taken" with rubbing. Especially make sure the edges are stuck down good. And there you have it. Try not to fold your sail near the numbers, but people don't fold their sails, do they?
I've done this for years, and I've found the numbers can stay on for years too. Much cheaper than professional numbers cut from sticky-back dacron.
Now, what are the chances of me turning up on Sunday without sail number?

Dr Duck