Large hailstones pelt Newcastle, in the Hunter region, as the weather bureau warns people across NSW to brace for flash flooding and destructive winds.
A hostage-taking incident is unfolding at the building used by Dutch radio station 3FM.
Dutch police have cordoned off the building in the city of Hilversum and have confirmed the hostage situation, public broadcaster NOS says.
The NOS says a man forced his way into the building after making threats to a couple outside.