Interesting thread.
Australia has a North-South spread equal to Norway to Egypt.
So the question of "coastal to inland" is not really all that important. The longevity of PLA out-doors is more related to the average number of hours of direct sunlight and ambient temperature. That varies in AUS between 5 hours day at 18 degrees C and 12 hours a day at 33 deg.
There are also places with temperatures in the high 40s for several weeks a year with 12 hours of direct sunlight for months on end and places with 4 hrs a day sunshine and low temperatures of -10 deg C.
I suspect that NO plastic is likely to survive much longer than a couple of years in AUS in all places - at least I haven;t found one yet.
Where I live (nice mild climate with 4 seasons) temperatures range from 0 deg at night (rare) in winter to 45 deg (rare) in Summer and no paint of plastic or anything other than a few metals survives outside more than a few years, depending on the colour. Black anything starts visibly deteriorating in weeks (if it doesn't melt) and white in a few months. Anything you want to last outside has to be stainless, aluminium or yellow metals (copper, brass, bronze) and electrolytically isolated to last decades. The same goes for paints. Red cars look like they are painted with red chalk after 3 years, silver or white cars may last 10 years before they look like they have chalked on paint.
So the exact outdoor material has to be chosen for each specific location - just like Europe and North Africa. Finnish Paint will look like crap soon in Cairo and Egyptian paint will fall off in small bits at the first sub-minus 20degree night in Norway...
By the way, in our tropics, 32 degrees constant temperature and humidity ranging from 0 to 100% - and the resultant fungal, algae and lychen growth is another completely unrelated issue of longevity of materials we are battling with.....
Just to give some more perspective to the problem.....
Cheers,
Joe
