The ANZ Heavy Traffic Index rose by nearly 10% last month, after a sharp drop in June.
The index, which measures heavy traffic flows on 11 roads and gives a picture of the current economy, surged a seasonally adjusted 9.6%, after a big storm in June dragged it down by nearly 8%.
The Light Traffic Index, a predicter of GDP six months ahead, rose 0.8% in July, after falling 2.1% in June.
ANZ senior economist Sharon Zollner said the bounce in July bodes well for economic growth in the September quarter.
However, she said the drought in February could cause some volatility in the June quarter GDP figures.