Daily rainfall totals of 30-50mm are forecast across the state during these weather events, while a severe weather warning for heavy rainfall is current for parts of Mallee and Northern Country forecast districts.
The bureau has issued minor flood warnings for the Kiewa, Loddon and Snowy rivers, while there is a flood watch for northern and parts of southern Victoria.
Major flooding is possible in the northeast from Friday afternoon.
There is also a gale-force wind warning for the east Gippsland coast on Thursday.
Further north in NSW, Sydney is set to break its all-time yearly rainfall record this weekend despite nearly three months of 2022 left.
The city is already experiencing its second-wettest year in the 164 years since rainfall records started being kept in 1858.
As of 7.30am on Thursday, Sydney is a bit more than 25mm off the all-time record of 2194mm set in 1950.
Rainfall totals of more than 50mm have fallen in less than 24 hours since 9am on Wednesday across Greater Sydney in areas like Hornsby.
Bureau of Meteorology meteorologist Jonathan How described the wild situation as "incredible".
"We are about one inch [25mm] off breaking the all-time annual record and that is extremely significant because records at the Sydney CBD site go back to the 1850s," he told Sunrise on Thursday.
"There's still more than two months to go this year, so Sydney is on track to break the record this weekend.
"Many across Sydney know it's been an incredibly wet year and that record proves that."
Osborne agreed that Sydney's record would fall by the weekend, while flood-affected areas across NSW are set for another deluge.
"Right the way through until midnight Sunday ⌠falls between 50 and 150mm are expected," she said.
"That will easily see Sydney take over to their wettest year on record and it's falling over catchments that certainly don't need it."
NSW SES has 47 flood warnings in place across the state. Fifteen are to "watch and act", the rest are "advice" warnings.
That includes a flood watch being issued by the bureau for possible minor to moderate flooding around Greater Sydney and the Illawarra along the Hawkesbury and Upper Nepean rivers.
Across Sydney, Wakehurst Parkway is closed in both directions due to flooding, while Audley Weir and Oxford Falls Rd are also closed.
Western areas around the state, including Forbes, Warren, Dubbo, Nyngan and Bathurst, have been advised to be on high alert for possible floods throughout Thursday.
The bureau said communities like these could experience more flooding over the coming weeks due to the heavy deluges they had had in recent times.
"Many communities that recently experienced flooding or are currently in flood will likely see rivers rise in the coming week," it said in a statement.
"The ground remains saturated, and any additional rainfall will cause streams and rivers to rise."
But state Emergency Services Minister Steph Cooke expressed confidence the government and SES were prepared for the situation.
"We are seeing challenges on multiple fronts across NSW at present. Across the western parts of the state we have got multiple river systems that are in floodwaters to some extent, whether that be minor right through to major," she told the ABC.
"We have resources positioned where they may be needed, whether that's aircraft positioned around the west of NSW, we have got high-clearance vehicles in certain communities, we have got more than 500 SES volunteers out in the field at the moment.
"It is going to be a challenging few days, but we are up to the challenge."
NSW SES performed four flood rescues and received 237 requests for assistance.
