Five hundred homes could go under overnight as the big wet drowns Townsville - with tens of thousands more properties at risk if the north Queensland flood crisis worsens as expected.

Police, soldiers and emergency services were door-knocking on Saturday in Townsville, the epicentre of the one-in-100 year event, warning more water is on its way.

People were warned to think about moving to safety before dark, particularly those in low lying houses.

“The window is closing very, very, very quickly,” acting chief superintendent Steve Munro told reporters.

About 300 homes were affected at about 1700 (AEST) on Saturday. “We are expecting that to rise to about 400 to 500 homes overnight out of a population of 80,000,” he said.

“If the rain continues overnight and into tomorrow, if we keep going the way we are today, we are talking about 10,000 to 20,000 homes.” More than the annual rainfall has fallen on parts of north Queensland in the past week, creating a disaster area stretching 700km along the coast from Cairns to Mackay. Premier Annastacia Palaszczuk has warned the next 24 to 48 hours “are crucial” and urged people to monitor warnings from authorities.

Overnight swift water rescue crews helped 80 people move to higher ground, and they spent Saturday guiding more through flooded streets.

The bulging Ross River dam was at 216 per cent capacity at 1700 despite gates being opened to let water out.

About 100 homes were evacuated near the dam as the water was released. Paul Shafer and his family lost two cars, a truck and a caravan when water was released from the dam, a risky move designed to spare the town from more widespread flooding.

He understood the decision but said it was demoralising to see the destruction at his Hermit Park park home where water flows through the ground level of his home.

“We have decided to stay rather than evacuate, we still have electricity but it will be a sleepless night ahead, that’s for sure,” he said.

The rain and flash flooding began a week ago causing power and phone outages, closing roads and businesses and inundating homes.

The flooding has begun to spread inland to drought stricken western Queensland where grazier Cameron Kennedy said a week ago he was desperately praying for rain - now he wants is for it to stop.

His Castle Hill property outside Winton is now an island surrounded by an inland sea after receiving “bloody heaps” of rain, some 348mm since Tuesday. Not too far from Winton, a grazier in a helicopter rescued four tourists trapped in a car after being stranded by the flooded Diamantina River. State Disaster Coordinator Bob Gee is urging people to stay out of the water and check emergency and weather warnings - which are updated regularly. Further north, coastal communities on the Gulf of Carpentaria are preparing for the highest tides of year and gale force winds.

ONE-ON-100-YEAR ‘CATASTROPHIC’ FLOODS

North Queenslanders woke to another day of torrential rain on Saturday, with officials predicting “catastrophic” record-breaking floods this weekend.

Officials are fearing totals of up to two metres of rainfall on a 700km-long stretch of coast from Cairns to Mackay.

Townsville sits at the centre of the massive downpour, with dozens of homes swamped by floods and schools and businesses forced to close.

More than 36,000 sandbags have been deployed around the area, with Council crews filling about 10,000 of them as the flooding intensifies.

Forecasters have warned that today could be the “most significant day” of the monsoon event, with the Bureau of Meteorology (BOM) warning communities in North Queensland that the heavy falls and flooding could last over the weekend and well into next week as the monsoon trough continues to influence weather across the tropics.

“A number of sites including Upper Bluewater (1230mm), Paluma (1181mm), Upper Black River (1034mm) and Woolshed (1008mm) have recorded more than a metre of rainfall over the past seven days," Queensland Flood Services Manager Victoria Dodds said.

“A Major Flood Warning has been issued for the Ross and Bohle Rivers where record flood levels are being recorded at Aplin Weir on the Ross River. Flooding of properties in low-lying areas is expected as early as this afternoon.

“Other areas of immediate concern include the Haughton River, south of Townsville, where we saw record flood levels reached at Major Creek earlier this morning.”

The BOM noted a number of roads are already impassable and swift-water rescue teams have been engaged where members of the community have been forced to travel through floodwaters.

An Emergency Alert flood message has been issued for residents in areas adjacent to the Bohle River, Saunders Creek and Stoney Creek and including the suburbs Deeragun, Jensen and Burdell.

Queensland’s flooded Daintree River reached a 118-year high this week. Emergency services reported rescuing 28 people from floodwaters in the past week.

“The vast bulk of the population will not have experienced this type of event in their lifetime,” State Disaster Coordinator Bob Gee told reporters, referring to the extraordinary flooding.

Townsville Mayor Jenny Hill described the torrential rain as a “one-in-100-year event” that had forced authorities to release water from the city dam. The water release would worsen flooding in low-lying suburbs, but would prevent the Ross River from breaking its banks.

Yesterday Premier Annastacia Palaszczuk said police would be given wider evacuation powers across 100km of the disaster zone.

She also said the decision to close 58 schools and childcare centres was to ensure public safety.

“It is safer if families are not trying to get to and from school,’’ she said.

“The bureau’s advice is, if this monsoonal weather continues, the next few days could see more heavy rainfall.”

The massive monsoonal deluge has caused landslips and flash flooding across the region over the past seven days.

Homes and businesses have been destroyed as flash floods washed through streets sweeping away cars, equipment and livestock.

Landslips have destabilised an apartment complex, blocked roads and caused homes to be evacuated.

More rain has been forecast across the weekend, with some areas likely to receive up to 400mm a day, as the overly active monsoon trough remains almost stationary.

Townsville City Council has advised intense rain may cause fast-moving and rapidly-rising water levels in these areas and lead to flash flooding. Residents are advised to move to higher ground if concerned.