Yass was experiencing flash flooding on Monday night, NSW SES said.
"Please take care around the area, there is water across the roads in a number of locations. We have received significant rain that has causing flash flooding," the emergency services agency said.
"Remember please do not drive or enter flood water as there are many hidden dangers."
Locals reported flooding on Wargeila Road, Brennan Street, Fairyhole Road, Goodhope Road and Laverstock Road.
"Goodhope Road closed at turn off," one person wrote on social.
"Do not attempt to drive past the bollards as fences have been washed across the road and can't be seen under the water."
The Bureau of Meteorology issued a severe thunderstorm warning for heavy rainfall and damaging winds at 6.48pm on Monday.
"Fast moving thunderstorms have developed ahead of a slow moving front extending across the Riverina and into the Upper Western," the alert said.
"Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding and damaging winds in the warning area over the next several hours.
"Locations which may be affected include Braidwood, Goulburn, Yass, Condobolin, Young and Cowra."
Canberrans have also endured a soggy Halloween on October 31, as the city caps off a record-breaking October with even more rain.
There have been 163 millimetres of rain in the month already, breaking the 1976 record of 161 millimetres, and there's more rain on the way.
Canberra had had 31mm of rain by 7.30pm on Monday.
The rain has put Tuesday's race at Thoroughbred Park in doubt with Racing NSW stewards set to conduct an inspection to assess the surface suitability for racing at 6.30am, according to the governing body.
Organisers are expecting a crowd of 3000 at the Melbourne Cup Race Day event - rain, hail or shine - the first unhampered by COVID-19 restrictions since 2019.
BOM meteorologist Helen Kirkup said there is also a chance of snow on Tuesday evening and Wednesday morning in areas above 1000 metres.
"Some of the Brindabellas could easily be seeing snow," Ms Kirkup said.
"Canberra itself could still see a couple of showers on Wednesday and Thursday, but clear from Friday into Saturday."
A flood warning for the Murrumbidgee River at Gundagai, Wagga Wagga, Narrandera, Darlington Point, Carrathool, Hay and Balranald was also issued on Sunday.
The river is already closed in the ACT after bacteria levels deemed unsafe were detected at several locations.
A warning for sheep graziers is in place in the ACT and a minor flood warning for the Snowy River.
The ACT SES is warning Canberrans to watch out for falling trees and powerlines due to the strong winds and wet soil.
The ACT bushfire season officially starts on November 1, after being delayed a month due to rain.
Damaging winds hit eastern Australia
Meanwhile, more than 14,000 people were left without power in Victoria after damaging wind gusts hit southern parts of the state, from the South Australian border across metropolitan Melbourne to Gippsland, on Sunday night.
The state's SES received more than 350 calls for help in 24 hours, mostly in outer eastern suburbs of Melbourne.
The Murray River remains in flood at Echuca, although water levels are slowly subsiding.
An evacuation order has been issued for Bogong Village near Falls Creek in the state's northeast, where a slow-moving landslide is active above the alpine settlement.
Across the Bass Straight, Tasmanians have been warned of the risks of flash flooding, winds of up to 110km/h and possible thunderstorms in southern parts of the state.
Coastal and elevated areas in South Australia are likely to experience damaging winds from late on Monday morning.
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