The deluge saw the Brisbane city gauge record 183 millimetres in the 24 hours to 9am Saturday, the most since records began in 1840.

Forecaster Kev Hutchins from the Bureau of Meteorology said it was also the city's wettest calendar day of any month since 1989.

"The May monthly average for Brisbane city is 71.2 millimetres, so we more than doubled that in one day," he said.

The biggest single rainfall was recorded at Caboolture, which received 333 millimetres. Of that, 277mm fell within three hours during Friday afternoon.

A number of places around South East Queensland recorded their wettest May days since 1996: Brisbane airport with 129mm, Archerfield with 142mm and 115mm at Toowoomba.

"Oakey had 102mm, their wettest May day on record, and they've been recording there since 1971," Mr Hutchins said.

"Their average is only 39.5 for May, so it really dumped down."

He said while severe, the rain system that drenched the south-east was not unusual.

"If you're going to get an east coast low, this is the time of year you're going to get it, autumn into winter," Mr Hutchins said.

"You often find those average figures for this time of year do occur in one big lump, and then the rest of the month tends to be dry."

He said the bureau had forecasted rains of between 50 to 150mm, with isolated falls of 200 to 300mm, which is what ended up happening.

The rest of this week, however, is set to be fine, sunny and with above average temperatures.

"The Brisbane city average maximum temperature is 24.3 degrees, and we're forecasting 27 for Monday, 28 on Tuesday and even 29 on Wednesday," he said.

"Then we're expecting it to drop down to something approaching average for May."

Mr Hutchins said there was some fog over Brisbane on Monday morning, which was expected to repeat and be heavier on Tuesday, but would burn off to reveal blue skies.