Almost a month's worth of rain hit the capital on Friday, in the wettest day of 2017.

While forecasters had originally expected half a month's rain to fall across both Friday and Saturday, the skies had other ideas, dumping about 33 millimetres on Canberra's city centre and up to 88mm in the west near Mount Ginini overnight.

People braving the rain on Commonweath Avenue. Credit:Elesa Kurtz

Bureau of Meteorology forecaster Helen Reid said Friday's soaking was something of a "one hit wonder", as the weather system moved more quickly than anticipated.

"It's a good amount to have in one night," she said.