I bought a HD leather jacket with vents.  I have always worn leather regardless of the temperature.

Someone posted a link a little while back where you can buy all of the HD jackets at a great price.

I have a Dririder Climate Control 2 and it is very good.

Its a mesh jacket with armour and removable liners. 

I will be buying a leather jacket also.

Some of the Harley leater Jackets have good ventilation.

 dhgate.com , alibaba.com are two china sites,never tried my self probably where the original jackets are made.Have a look and see lots to choose from.

 Also what are their sizes like if they say xxl is it a xxl in Australian size or smaller etc

I've got an IXON fabric jacket . I'ts like those russian dolls with all the liners it has, but when you strip it right down it's a great summer jacket.No hotter than a long sleved shirt but with back shoulder and elbow protection.

Leather jacket with vents for me

Have a browse here ... https://www.leatherup.com/l/Motorcycle-Jackets/11.html ... I found their leather jackets were cheaper than the ones from China.  Shipping is a little pricey but it still works out much cheaper than buying in Aust. All their leather jackets and some of their fabric jackets are Xelement ... we just went to a local shop that stocked Xelement jackets and tried them on for size before ordering. Quality is excellent.

I wear a jacket from a mob called traxion motorcycle apparel who are local in adelaide, the one I have is a cordura jacket and it is brilliant in the freezing cold winter mornings and the wet aswell as being good in the hot weather. Traxion also do Cordura mesh jackets that come with removable quilted liners and body armour aswell as wet weather covers, I am looking at getting one of these mesh ones for summers in SA. They can be found here http://www.traxion.com.au/

Traxion sponsor our Rally that we hold every year and every year we hear that the people that won last years prize have never had a Jacket so good before.