Australians are sweltering, freezing and getting blown away by extreme weather conditions, with a wild combination of a heatwave, snow and winds smashing the east coast as NSW floodwaters continue to rise.

Residents on the east coast are dealing with yet another burst of severe and unusual weather just days out from summer.

In Brisbane, a cooler spring was swept away almost instantly on Monday as the mercury soared to a top of 35 and brought the threat of severe storms.

A heatwave warning was issued for Queensland with scorching temperatures expected to hit the mid 30s, and possibly 40 degrees, over northern Queensland for much of the next week.

Weatherzone said it was at least the sixth Australian snowfall of note in October and November, in what had been a “very, very snowy spring by Aussie standards”.

Weatherzone meteorologist Joel Pippard blamed it on an “unusually strong and cold stratospheric polar vortex”.

Meanwhile, there have been damaging winds across the south-eastern states.

There were wind gusts of 70-90km/h in parts of Melbourne late on Sunday and into Monday, leading to trees toppling in some parts of the city. Small hail was also reported in some suburbs in Melbourne on Monday morning.

Another severe weather warning was issued for much of NSW’s south, including Sydney and the Illawarra, Riverina, Snowy Mountains and ACT regions.

Damaging westerly winds averaging 50-70km/h with peak gusts topping 90km/h are likely across elevated parts and also eastwards to the coast and across the Goulburn region.

For the remainder of the warning area, including Sydney and Canberra, damaging gusts in excess of 90km/h were possible on Monday.

Showers or thunderstorms are also predicted across the Riverina and south-west slopes.

Tweet from @tarnmoore

Meteorologist Jonathan How said such cold and windy conditions were unusual late in spring and urged people to listen to warnings and stay away from trees.

“With the winds, because everything is so wet, we are expecting to see trees and even powerlines topple more easily today,” he told ABC TV on Monday.

“The winds will continue into tonight and possibly even into tomorrow morning as well. By tomorrow, we should see some of the strongest winds start to ease off.”

The flood risk remains in central western towns but no significant rain was expected in saturated catchments this week.

The NSW SES issued three fresh evacuation orders for parts of the state’s central-west and the Riverina on Monday, ahead of expected dangerous major flooding.

Residents in parts of West Condobolin were ordered to leave immediately before roads were cut by floodwaters.

On the Murray River, residents of the isolated town of Moulamein were warned to leave by 2pm on Tuesday. They were told there would be only one chance to leave under escort.

Further east on the Edward River, residents in 10 streets in Deniliquin have been given until 10am Wednesday to leave.

New focus for flood fears as river rises

In Forbes moderate flooding continued on Monday. But the real concern this week is downstream at Condobolin, where the Lachlan River is expected to peak on Wednesday.

Authorities are keeping a close eye on the three-kilometre levee around Condobolin’s CBD. SES Chief Superintendent Dallas Burns said it was expected to hold up to the current peak.

The SES was working closely with local councils to ensure levees were maintained.

“Obviously with this flooding coming up and down so often over the past months there is quite a bit of damage happening to those levees just from erosion, so that’s something we’re very concerned about,” he told ABC TV.

As floodwaters recede in Forbes, the town is transitioning to the recovery stage. NSW Emergency Services Minister Steph Cooke said damage assessments were being conducted, with the aim of allowing some people to return to their homes.

The Australian Defence Force is helping with sandbagging and cleaning out of homes, although some parts of Forbes remain waterlogged.

Of 400 damage assessments completed so far by the SES, half of the properties had been marked as “damaged”.

As the peak moved down stream, Ms Cooke said already isolated communities were bracing for severe water level rises.

“Our thoughts are with those communities,” she said.

“We know that you’re going through a hard time and will continue to stand with you throughout the response and the recovery phase.”

To support communities, nine recovery assistance points were opened this week including in include Eugowra, Orange, Parkes, Gunnedah, Cudal, Wagga Wagga, Narrabri and Moree.

The multi-agency hubs are designed to help flood-impacted individuals, families, farmers and business owners begin the clean-up, rebuilding and recovery process.

-with AAP