A thunderstorm caused widespread power outages, train and flight delays across Sydney.
The city and its surrounds were hit with about 75,000 lightning strikes in three hours as a the storm rolled through in the early afternoon.
About 27 millimetres of rain fell at the airport in three hours, 28 millimetres fell at Gosford and 25 millimetres fell at Badgery's Creek.
About 13,000 homes lost power, mostly in Sydney's north.
Four people were hospitalised after the tree they were sheltering under at the entrance of the Royal Botanic Garden was struck by one of the lightning strikes just before 1pm.
Birdsville's Diamantina River is experiencing a major flood after ex-tropical cyclone Lincoln crossed the coast as a category 1 storm between the Northern Territory-Queensland border and Port McArthur.
The Diamantina River is usually a thin river running through the outback town but yesterday it was expected to peak at 7.6 metres.
The Bureau of Meteorology put out a major flood warning.
BoM expected the river to peak on Sunday morning and begin falling over the next few days.
Birdsville Roadhouse posted the photos to Facebook, showing locals excited to see plenty of water in the desert.
Authorities encourage everyone not to drive through floodwater.
Victorians have woken to severe storm damage after gale-force winds and golf-ball-sized hail battered parts of the state.
Click through to see the storm damage.
The severe storm caught many residents by surprise when it hit.
The damage was widespread with requests for help received from Clayton to Lara.
Multiple cars in Mulgrave have been completely damaged after a gum tree toppled over.
This roof was blown off a home in Mount Waverley.
Powerful winds downed trees across the city, including here in Clayton.
Many businesses have lost power following the storm.
Golf-ball-sized hail, flash flooding and severe winds ripped through large parts of Melbourne.
Wind gusts reached up to 130km/h in parts of the state.
Melbourne descended into darkness before the storm hit the city.
Traffic lights across Melbourne were impacted by the storm activity, including at this intersection in Glen Waverley.
Almost 300,000 homes and businesses lost power after major electrical transmission lines and power generators failed.
The storms caused the collapse of six transmission towers near Anakie, between Geelong and Bacchus Marsh, and tripped an entire power station in Gippsland.
The weather event has been labelled as "one of the largest outage events in the state's history".
Stunned residents have shared the aftermath of the "chaotic" storms, that tore sheds apart and flung trampolines through the air.
Trees were even ripped out of the ground.
Emergency services received more than 2,750 calls for assistance within 24 hours.
Many calls were for tree damage.
About 240km away - residents were dealing with an entirely different weather event.
Two bushfires threatened communities near the Grampians National Park, with some residents told it is "too late to leave".
Jumping off the pier to cool off was popular in South Melbourne, as Victoria experienced its hottest day of summer.
The state sweltered with temperatures soaring above 40 degrees in the north.
Parts of South Australia and New South Wales also recorded some of their highest temperatures in up to three years, according to the Bureau of Meteorology.
But the heatwave was short and sweet, with cooler temperatures arriving last night.