white coatee as a warm weather option

[Dileasgubas]

I have a fair number of formal events to attend this coming Summer and was wondering about the appropriateness of a white coatee. Is such a thing appropriate or a mixing of styles? I came across the included photos (one from XMarks and another of what appears to be an Australian mess uniform) - both look to be quite sharp; however, I don't see them commonly for sale on suppliers' websites.

So, I was wondering what tends to be done when the weather gets hot? My current jacket options are limited to barathea, tweed and wool in dark tones, none of which are particular appealing for a hot Summer evening.

Suggestions would be welcome.