Fire crews were called to Bukulla St, Wacol, just before midday to rescue someone trapped on a vehicle in about 0.8m of rapidly flowing water.

It took two swift-water technicians to pull the person to safety. Paramedics examined the person on-site but found no injuries.

RT @sallyeeles Swift water rescue at Wacol pic.twitter.com/FNFedILEQV http://t.co/exCYduYBBP — ACREM (@cbemergency)  January 23, 2015

Fire crews have been called to five other water rescues in Brisbane since heavy rain started falling overnight on Friday.

Flooding, road closures and a rock slide were just the start of the problems caused by heavy rain pelting the state's south-east.

More than 20mm has fallen in Brisbane city since 9am, adding to more than 40mm overnight. But many northern suburbs had much heavier falls.

The rain has flooded roads, caused traffic headaches and even issues with a sewer pit, affecting traffic on one of Brisbane's busiest roads.

Albert Street Goodna. Pic credit: Paul Tully #bigwet #bneweather #mmmbrisnews. Tweet us your flood pics (safely). pic.twitter.com/lVHqoPlSao — Triple M Brisbane (@TripleMBrisbane) January 23, 2015

Falls are easing in Brisbane but a lunchtime high tide combined with continuing rainfall to flood low-lying areas.

More than 20 roads throughout the city are affected by either flooding, crashes, signal faults or potholes and debris.

Paramedics have been called to five separate crashes on the Warrego Highway near Ipswich since 6.30am and others at Deception Bay and Bracalba.

Police are at the scene of a traffic crash on the D'Aguilar Highway at Bracalba. http://t.co/y8YqbmvH16 #bigwet — QPS Media Unit (@QPSmedia) January 23, 2015

A multi-vehicle crash on the Pacific Highway near Holland Park is causing big delays southbound and there's been a rockslide on the Gold Coast near Mudgeeraba.

An earlier incident with a sewer pit on the Milton Rd exit from Hale St has been fixed but not before the exit had to be closed, causing extensive delays.

Brisbane City Council initially said the pit collapsed but a Queensland Urban Utilities spokeswoman said that was not the case.

A maintenance hole cover broke and fell into the pit, she said.

RACQ is warning people to check where they parked their cars to avoid flooding.

"We expect the normal areas like Newstead, Teneriffe, in the CBD and Woolloongabba and Greenslopes areas, which often flood because they're near those creeks and rivers, that they will also flood come 11.30, 12 o'clock when the high tide hits," spokeswoman Lauren Ritchie said.

"Kingsford Smith Dr has already been heavily affected this morning by water and by river so obviously our message to motorists is 'if the warnings are there, don't push your luck or your life' because those road closures are there for a reason."

Authorities have reported several cars either travelling through flood waters or becoming stuck trying to do so.

We can't say it enough, it's not worth the risk.Forget driving through flooded roads! #FloodedForgetIt pic @PaulTully pic.twitter.com/IJ17Wi0Xnp — RACQ (@RACQOfficial) January 23, 2015

Car stuck in flood waters - Old Pacific Highway, Oxenford. #bigwet — QPS Media Unit (@QPSmedia) January 23, 2015

Paradise Rd, Larapinta; Muriel Ave, Moorooka; Cliveden Ave, Corinda; and the Strathpine Road off-ramp at Bald Hills were all closed to traffic as at 11.30am Friday.

Water was still over the road at Albion St and Ipswich Rd, Woolloongabba; Bennetts Rd, Norman Park; Creek Rd, Carina; Holdsworth St, Coorparoo and a handful of other locations.

The heaviest rain has eased over Brisbane, with major falls now further south on the Gold Coast and inland, as some locations cop peak hourly falls of about 40mm.

The Bureau of Meteorology issued its latest severe weather warning just before 11.30am, saying the rain could combine with the high tide around midday to cause some inundation of vulnerable coastal areas.

Affected areas include the Gold Coast, Brisbane, Coolangatta, Ipswich, Moreton Bay and islands, Beenleigh, Caboolture and Caloundra.

"There's a good potential for when the tide comes up in some low lying areas for some creeks to flood," senior meteorologist Pradeep Singh said.

"The heavier falls are shifting further south towards the Gold Coast.

"We expect more rain but not as heavy as we had last night."