Major highways have been cut off, theme parks have closed and residents are flooded in as up to 300mm of torrential rain bucketed down on southeast Queensland overnight.

A severe storm warning was issued by the Bureau of Meteorology after intense rainfall from a mega cell lashed the state, extending from the Sunshine Coast down to the Gold Coast. The heavy rain caused "life-threatening" flash flooding on major roads as it fell overnight.

"Intense rainfall that may lead to dangerous and life-threatening flash flooding is likely," a BOM spokesman warned.

In some parts of the region, where in excess of 200mm fell, the average January rainfall was doubled in one night.

The severe weather warnings have now been lifted, as the slow-moving cell now affects northern New South Wales and moves offshore, but Queensland Fire and Emergency Services has advised people to seek shelter, beware of fallen trees and powerlines and not to risk travelling through flooded areas.

Police have received more than 50 reports of flooded roads across the Gold Coast this morning.

Parts of the Pacific Motorway have been closed, and the Gold Coast Highway and Cunningham Highway are blocked.

Gold Coast theme parks MovieWorld and Wet n Wild will be closed today because of severe flooding.

"Please be aware that due to severe weather and flooding, Warner Bros. Movie World will be closed today for the safety of our guests and team members," a post by the theme park on Facebook read.

VICTORIA

Residents in a remote area of Victoria's Alpine Region have faced an anxious wait overnight after an "evacuate now" warning was issued Friday night.

While parts of Australia's east are soaking in some much-needed rainfall, more than a dozen blazes continue to rage in Victoria, where residents were displaced overnight.

Most of the fires ripping through the state, predominantly in East Gippsland and the northeastern alpine region, were burning at a "watch and act" level or low, but emergency warnings were issued for fires near Mount Buffalo in Victoria's alpine region, and briefly for Bulart, in the state's southwest.

The emergency warning for an out-of-control grass fire at Bulart was downgraded to a "watch and act" alert early this morning.

However, residents there and at nearby Cavendish, Gatum and Melville Forest were warned to stay close to a building so they could shelter if conditions changed.

An evacuation order was earlier issued for the blaze near Mount Buffalo.

Residents living in Buffalo Creek, Merriang and Merriang South were told strong and erratic winds had significantly increased fire activity near them, and it was recommended they evacuate.

The warning came as a registration service has been established for people who fled Mallacoota, Genoa and Gipsy Point and want to return now conditions have improved.

When it is safe to do so, emergency services and the Australian Defence Force will begin flights or escorted road transport into Mallacoota and surrounds, Victoria Police have confirmed.

Incident management specialists from the US and Canada are set to arrive at Melbourne Airport on this morning, before being deployed to fires in the northeast and East Gippsland.

Smoke is also expected to return to central Melbourne on Saturday and Sunday as easterly winds cross firegrounds.

Bureau of Meteorology senior meteorologist Dean Stewart said it was unclear how bad the situation would be.

"Nevertheless at least some smoke haze in the area," he said on Friday.

Emergency Management Victoria has forecast the air quality will range from good to poor across the state, with areas closest to the fires experiencing the worst haze.