Eucla 50.67 degrees C.
“The highest temperature ever recorded under a Stevenson screen in Western Australia was 123.2 at Eucla in 1906. The Stevenson screen was used by all weather bureaus in the Commonwealth for securing official shade temperatures. ” Bold mine.
From The West Australian Wednesday 25 July 1934 Page 18.
According to the BOM page here as at 14th July 2012 the highest temp there was 47.9 C on the 3rd Jan 1979.