South-east Queensland is set for a deluge on Friday, in what could be the biggest wet since Cyclone Debbie hit the state in late March.

Rainfall totals of 100 to 200 millimetres are forecast for the coast between Rollingstone and Gladstone and inland to parts of the Burdekin and Fitzroy catchments, and the Bureau of Meteorology said isolated totals of up to 400 millimetres of rain is possible.

A flood watch for those areas was issued by the bureau and Fire and Emergency Services Minister Mark Ryan said Queenslanders should not risk driving through floodwater.

"The Bureau of Meteorology is predicting that this will be the largest rain event in Queensland since Tropical Cyclone Debbie and there is the potential for flash flooding throughout the flood watch areas," he said.

On Thursday BOM meteorologist James Thompson said parts of north Queensland had already experienced rainfall totals upwards of 100 millimetres by Thursday evening, and that weather system would track south through Friday and Saturday.

"Today we saw some places up near Bowen get above 100 millimetres, and that system's moving south, so tonight we'll see the rainfall start to pick up south in places south of Gladstone," he said.

"Through tomorrow it will probably continue with some showers, maybe the odd thunderstorm as well, and some rain through the day, and then clear off the coast on Saturday morning."

By 7.30am Friday, barren Townsville had been doused in 102 millimetres, more than three times its May average.

Alva Beach, near Ayr, had picked up 190 millimetres with 109 millimetres falling in Proserpine, south-west of Airlie Beach.

Mr Thomspon said the Gold Coast and Sunshine Coast hinterlands would experience the most rainfall in the south-east, but Brisbane could also see rainfall of 100 millimetres or more.

"Anywhere in the south-east could see rainfall totals in excess of 100 millimetres, but more likely 25 to 75," he said.

Redcliffe had already picked up 43 millimetres overnight, with 28 millimetres in Beerburrum.

But for those heading to the Paniyiri Festival at West End on Saturday, some good news: the rain is expected to clear up by Saturday morning.

"Saturday morning we're probably only going to see rainfall in the far south-east of the state, so probably right on the border," Mr Thompson said.

"So through Saturday we're just looking at the usual possible shower with a little bit of moisture still lingering around but nothing significant."