I think it all depends on the particular Austin rose. I visit the Inez Grant rose garden in Balboa Park San Diego quite often in zone 10a, and a number of them look good even in hot temps. Mary Rose always looks great even in August, so maybe Winchester Cathedral could be a good choice seeing as it's a white sport of Mary Rose. Also Lady Emma Hamilton, Olivia Rose Austin are two others that come to mind that look good here even in hot temperatures. Lichfield Angel seems to always looks good and healthy also, but doesn't seem to have quite as many blooms as the others. Here are a few photos I took in August of this year.
Mary Rose
Litchfield Angel
Darcey Bussell always looks good
