Lightening struck power lines in Blacktown, about 1.15pm, blacking out traffic lights, businesses and hundreds of homes.
Lights at the corner of Prince Street and Third Avenue were out as were lights on Sunnyholt Road.
Endeavour Energy maintenance workers have restored power to most parts of the northern side of the city centre.
Po lice did not arrive to direct traffic.
Cars and trucks narrowly avoided each other at busy intersections for about an hour in heavy rain.
One eye witness said there were three lightening strikes within 30 seconds, and that a large cloud of smoke rose above apartment buildings on Prince Street, near Third Avenue.
Endeavour Energy workers said about 30 blocks were without power.