Weatherzone meteorologist Sam Brown said conditions should remain dry in Canberra until late on Saturday afternoon when showers would develop before "dumping" rain into Sunday morning.

"We’ll see up to 10mm on rainfall on Saturday evening with anywhere between 20 and 40mm on Sunday and up to 10mm on Monday morning easing into the afternoon," he said.

Mr Brown said thunderstorms were a possibility on Saturday night and Sunday afternoon although this was only a small chance.

"Winds should remain light to moderate over the weekend although they may become a little gusty on Monday but nothing too significant," he said.

The Bureau of Meteorology’s Sean Carson said there was a good chance Canberra would receive more than the August average rainfall of 45.9mm by Monday afternoon.

"The rainfall is not likely to start in Canberra until late Saturday round sunset and the bulk of the rain should fall overnight and on Sunday morning – that’s a solid 12 to 18 hours of soaking rain," he said.

Mr Carson said the weekend would bring the largest amount of rainfall to drought-stricken parts of New South Wales and Queensland, providing much needed relief for farmers and communities.

"Most of inland New South Wales and southern Queensland are looking at similar figures where they may reach their average August rainfall in just a few days," he said.

Mr Brown said this weekend would bring the most rainfall Canberra since the 10.8mm recorded on July 16, with small showers of less than 1mm recorded on August 2, 5 and 9.

"Temperatures should increase overnight on Saturday to about 3 degrees by Sunday morning although temperatures should stay around freezing on Saturday morning," he said.

"Daytime temperatures on Saturday should hover around 15 degrees before rain and cloud appear late in the afternoon, dropping to 13 degrees on Sunday with cloud cover."