Storm clouds and dust can be seen in the sky above as people walk at dusk along Mollymook Beach, south of Sydney March 5, 2014. (Photo by David Gray/Reuters)

A Virgin Blue Boeing 737-800 aeroplane flies past storm clouds shortly after taking off from Sydney Airport May 9, 2013. (Photo by David Gray/Reuters)

Storm clouds pass over Manly's Fairy Bower beach on Sydney's north shore as locals (L-R) Matt Fleming, Larry McMurridge and George Stantschef look on, March 5, 2014. The clouds, pushed along by a south westerly wind, generated little rain before being swept out to sea. (Photo by Will Burgess/Reuters)

A wave-like cloud looms over Sydney's Manly Beach during an afternoon storm front, March 5, 2014. (Photo by Will Burgess/Reuters)

A large storm cloud covers the Sydney CBD on March 5, 2014 in Sydney, Australia. A severe thunderstorm warning was issued for the Sydney metropolitan area late this afternoon with heavy rainfall due to cause flash flooding in areas. (Photo by Cassie Trotter/Getty Images)

A storm cloud passes over bathers who prepare to leave Sydney's Manly Beach during an afternoon storm March 5, 2014. The storm, which generated little rain but high gusts of wind, was blown out to sea. (Photo by Will Burgess/Reuters)

A giant storm cloud can be seen in the sky above swimmers near Mollymook Beach, south of Sydney March 5, 2014. The storm generated heavy rain and high gusts of wind. (Photo by David Gray/Reuters)

A large storm cloud covers the Sydney CBD on March 5, 2014 in Sydney, Australia. A severe thunderstorm warning was issued for the Sydney metropolitan area late this afternoon with heavy rainfall due to cause flash flooding in areas. (Photo by Matt Blyth/Getty Images)

Storm clouds and dust can be seen in the sky above a woman as she walks at dusk along Mollymook Beach, south of Sydney March 5, 2014. (Photo by David Gray/Reuters)