Queenslanders have woken to a chilly morning on Saturday with minimum temperatures up to six degrees below July averages.
Cold air pushed north by a high pressure system is expected to cause frosty temperatures throughout the state's southern half.
The Granite Belt, including Oakey and Stanthorpe, is forecast to drop as low as minus six degrees Celsius in the early hours of Saturday morning.
Brisbane temperatures are also expected to plummet with overnight lows expected at 6C on Saturday and Sunday.
The cold snap moved in on Friday with Roma, west of Brisbane, dropping to minus 1.7C on Friday morning.
Bureau of Meteorology forecaster Chris Joseph said the cold air is expected to penetrate much of the southern half of the state and possibly up into the lower regions of the Gulf.
"We're sort of drawing a line of anywhere south of Boulia to Rockhampton, anywhere south of that latitude is the area in the frost-prone zone I guess you'd call it," Mr Joseph told AAP.
Daytime temperatures are expected to be stable around 20C throughout the south-east but the bureau expects cold overnight temperatures to persist until early next week.
King tides are also expected to hit Brisbane with a peak of 2.74 metres expected at 10.52pm on Saturday.
Brisbane City Council is warning minor localised flooding could be experienced in bayside, riverside and low-lying nearby suburbs.
Council is warning residents in those areas to avoid parking their cars on the street during the high tides.