Sydney, Melbourne, Brisbane weather: More storms on the way, when it will strike

A massive afternoon thunderstorm has smashed Australia's east coast, sparking widespread chaos for the commute home.

The wild weather hit Sydney shortly after the Bureau of Meteorology issued a severe storm warning, plunging the harbour city into darkness by 4.30pm.

The thunderstorm is expected to bring heavy rainfall of up to 60mm which could lead to flash flooding, large hail and damaging wind gusts.

The inland Hunter, Central Coast, Southern Highlands and Illawarra regions are also in the firing line.

Brisbane and Melbourne also felt the force of Mother Nature on Wednesday as severe storms whipped across parts of Victoria and south-east Queensland. 

A broad low pressure system over southern inland New South Wales began drifting southeast late Tuesday, bringing thunderstorms to Victoria and the ACT

'A second low pressure centre is expected to develop somewhere off the southern coastline of NSW by Wednesday morning, causing a stream of moisture-laden winds to flow over southeast NSW and eastern Victoria,' Weatherzone meteorologist Ben Domensino said.

'This onshore flow will be drawing moisture from the "warm blob" to the east of Bass Strait, which is likely to enhance rainfall.'

'Rain should increase into Wednesday morning as the low develops and showers will persist into Thursday for some areas. 

'Six-hour rain rates could reach 50 to 150mm on Wednesday morning and accumulated totals may exceed 200mm by the end of Thursday.'

Sydney

Sydney is set to see the effects of the second low on Wednesday with possibly severe thunderstorms spread throughout the city.

'The rain that was occurring this morning should have largely cleared and the city will see a bit of sunshine and humidity,' Weatherzone meteorologist Brett Dutschke said.

'Thunderstorms will develop in the west this afternoon and will be scattered towards the east.

'Those storms could bring flash flooding, damaging winds and large hail but will clear out to see later in the evening.'

Further storms are expected to develop later in the week alongside drizzly showers on Saturday and Sunday.

'There's the potential for storms tomorrow afternoon, Saturday afternoon and on Sunday.' Mr Dutschke said.

That wet weather is forecast to be coupled with maximum temperatures in the high 20Cs.

Several regions in NSW are at the highest risk of flash flooding on Wednesday.

'The South Coast, Illawarra and Snowy Mountains have been getting a lot of rain and there's a high chance of some flooding,' Mr Dutschke said.

'There have already been a few places today that have picked up more than 200mm of rain.

'Ulladulla has seen 195mm. Goulburn had its biggest rain in 10 years at 98mm.'

Canberra

Australia's capital has already copped large amounts of rain from the systems with Canberra recording its highest daily rainfall in almost four years on Tuesday at 45mm.

'The city has more rain to come today' Mr Dutschke said.

'There's the possibility of a storms today and rain that will last through to Sunday.'

Wednesday's storm is expected to dump up to 60mm over the city before the skies partially clear to showers on Thursday.

Temperatures are set to plummet with a minimum of 12C and 11C forecast through to Sunday. 

Melbourne

Melbourne is forecast to see up to 20mm of rain alongside strong winds on Wednesday.

'Rain in Melbourne will continue for much of the day,' Mr Dutschke said.

'It will probably clear from most areas in the late afternoon and evening but there's still the chance of odd showers after that.'

Showers are expected to stay over Melbourne through to Saturday with temperatures ranging from 15C to 19C.

Sunday is set to be slightly warmer when the skies partially clear with a top of 24C.

Brisbane

Possible storms are set to hit Brisbane on Wednesday and Friday with a sunny day in between on Thursday.

The system over Brisbane on Wednesday could develop into a severe thunderstorm with winds reaching 15 to 20km/h in the middle of the day then becoming light in the late evening.

Unfortunately, the weekend isn't looking much clearer with showers forecast from Saturday to Monday.

A low-intensity heatwave sitting over far northern Queensland is expected to began creeping down the coastline on Tuesday and is expected to cover the entire stretch by Wednesday.

Some isolated regions could experience severe to extreme heatwave conditions with the far northeast to be the worst affected.

Adelaide

Cloudy conditions are set to hang over Adelaide through to Sunday.

The city has a very low chance of seeing any rain this week.

Temperatures are set to sit between the low teens and mid 20Cs. 

Hobart

Showers with low rain totals are forecast to fall over Hobart through to Sunday when the sky partially clears to cloudy conditions.

Perth

Perth could see a possible morning shower on Wednesday near the coast.

Light southwesterly winds over the city could reach 15 to 25km/h in the middle of the day then ease in the late evening.

Clouds hanging over Perth on Thursday are forecast to clear for a sunny Friday and Saturday.

Darwin 

Darwin is still in the thick of its wet season with storms forecast through to next week alongside maximum temperatures in the low 30Cs.

A low-intensity heatwave is expected to affect the Top End through to Friday.