Extreme weather warnings for Canberra and Queanbeyan

Heavy rain is expected to fall across the weekend in Canberra.

Weatherzone meteorologist Kim Westcott said up to about 65mm would hit Canberra's city centre on Saturday, in the wettest day since June last year. That's more than a month's worth of rain in a single day.

More than 21mm had fallen on Saturday by 8.30am, after 7.8mm fell on Friday.

Angle Crossing is closed due to the wet weather.

The ACT State Emergency Service (ACTSES) has received 23 calls for assistance after heavy rain since 5pm on Friday. ACT Fire and Rescue has assisted with the response, though no injuries or serious damage have been reported.

Most of the call outs related to fallen trees, backyard and garage flooding as well as leaking roofs.

The ACTSES has advised people not to climb onto roofs to remove leaf litter in the wet conditions.

Warnings from the Bureau of Meteorology said a tropical, warm and humid airmass over New South Wales will interact with a complex low pressure system, likely leading to heavy rain and the risk of flash flooding.

The warning extends to the ACT and Snowy Mountains districts, as well as the Riverina, South West Slopes, parts of the Lower Western, southern parts of the Central West Slopes and Plains and the western parts of the Southern Tablelands.

A flood warning has also been issued for Queanbeyan and Molonglo Rivers.

"The heaviest falls are mostly expected to be during the latter half of the day on Friday, and throughout Saturday," the warning said.

Rainfalls in excess of 100mm are likely over the 48-hour period, with localised falls in excess of 200mm possible in some parts of NSW.

Locations which may be affected by the wild weather include Yass, Condobolin, Wagga Wagga, Albury, Young, West Wyalong, Tumbarumba, Deniliquin, Griffith, Hay, Narrandera, Thredbo and Canberra.

Director of Roads ACT Ken Marshall reminded road users to exercise caution when travelling.

"If a high level of rainfall occurs, it is possible a number of rural roads could be affected, along with some unsealed reserve and forestry roads, such as fire trails," Mr Marshall said.

"For your own safety, please obey all directions from traffic management staff and signage.

"Motorists should drive to conditions. Do not attempt to cross a flooded road, bridge or causeway and if driving becomes too difficult pull over safely to the side of the road and wait until conditions improve."

Prime Minister Malcolm Turnbull was among political leaders reminding Australians not to drive, ride or walk through flood water.

On Thursday, forecasters warned heavy rains will lash the capital this weekend, as a significant storm system sweeps across Australia's south-east.

The conditions has meant a number of events have been cancelled on the weekend, but the Christmas in the city celebrations are going ahead.

Residents are advised to move vehicles under cover or away from trees, secure or put away loose items around their house, yard and balcony and to keep at least eight metres away from fallen power lines or objects that may be energised, such as fences.

For help in floods or storms call the ACT State Emergency Service on 132 500. In a life threatening emergency call 000.

Events cancelled or postponed due to wet weather