Unseasonably cold conditions are expected across large parts of Western Australia on Friday, as an icy pool of air from the southern ocean sweeps across the state.
Bureau of Meteorology forecaster Jessica Lingard said maximum temperatures in Perth and parts of the central Wheatbelt and Great Southern will be between eight and 12 degrees below average.
Perth is forecast to reach just 17 degrees on Friday – a temperature not experienced in November in more than 20 years, and comes close to a record-low maximum temperature for the month.
The city's lowest maximum on record for November was 16 degrees, recorded on the 8th, in 1995.
For other parts of the state, maximum temperatures are barely making it into the double digits.
Mount Barker, in the Great Southern, is forecast to reach just 12 degrees.
Meanwhile Dalwallinu, in the central wheatbelt, is forecast to reach 17 degrees – 13 degrees below its November average.
Ms Lingard said the cool change was being driven by a cold front, set to reach the south-west Capes late on Thursday.
"We're looking at a cold pool of air behind that front," she said.
"Typically we see that a lot further south but this time it is bringing that cold pool right up.
"All the winds are almost a directly from the south or south-west, so it's that cold air from well south of the country."
Rainy weather likely to hold up harvest
The system is also expected to bring decent rainfall to southern parts of the state, including to grain growing areas who have now begun harvest.
Ms Lingard said Perth was expecting between 10-15 millimetres of rain, while the southern coastline, from Augusta to Bremer Bay would see the highest figures with up to 20 millimetres forecast.
"And we'll also see rainfall pushing all the way through the agricultural region, and obviously that's a bit of an issue for the farmers as they are trying to get their harvesting done," she said
"The good news is it does dry up very quickly, so from Saturday onwards and then the temperatures returning to even some 30's for the early parts of the new week."
From west to east
While the rain might be a nuisance for grain growers in WA, for the south-east of the country where catchments are already full to the brim it is much more serious.
Major flooding is ongoing across numerous rivers of inland New South Wales, with flood warning current all across the state.
Many rivers across central and eastern Victoria are also experiencing minor to moderate flooding.
Ms Lingard said an earlier cold front, which swept over the state on Wednesday night, was now headed east and would likely to contribute to further rainfall there during the weekend.
"All of our systems do travel from west to east so it's inevitable it will reach them," she said.
"The system that went through (Wednesday) night is going to be the one that causes the most disruption to the eastern states.
"That will reach Victoria and southern parts of NSW on Saturday to those regions bringing more unwanted rain," she said.
Flood affected areas of central and northern New South Wales, however, are only expecting light falls from the system with the focus of rainfall through Tasmania and Victoria.
