Perth has had its wettest January day in 18 years, copping almost 10 times the average rainfall for the month in a single day.
Perth recorded 96 millimetres of rain since 9am Monday, courtesy of the remnants of ex-Cyclone Joyce making its way down from the north-west. On average, January receives just 9.7 millimetres.
Rottnest Island received 142 millimetres and Swanbourne 139 millimetres as the massive low-pressure front rolled over the city.
The rain caused a severe weather warning on Monday evening for Perth, Northam, Gingin, Lancelin, Yanchep, York and Rottnest Island and a flood warning for parts of the Gascoyne, Central West and Lower West.
State Emergency Services answered more than 220 calls for help, mostly damage-related.
The rain caused a commuter nightmare, with sections of the Kwinana Freeway, Mitchell Freeway and Great Eastern Highway flooded during peak-hour traffic, causing lanes and exits to be closed.
Some smaller cars were unable to use sections of the freeway further south because of the depth of the puddles.
Main Roads WA traffic management was called in to deal with the motorists attempting to navigate the conditions.
The downpour caused a string of prangs in O'Connor, Willetton, Mount Lawley, Morley and Albany Highway, causing further closures.
Traffic signals were also blacked out on Guildford Road, Lord Street, Walcott Street, North Lake Road, Omeo Street, Shepperton Road, Albany Highway, Great Eastern Highway and other parts of the Perth metropolitan area.
While the worst of the ex-Cyclone's wrath is expected to be over, the rain is set to continue on Tuesday, with up to 20 millimetres expected.
Perth's 7 day weather forecast
Tuesday: 19 - 31, showers and the chance of a thunderstorm
Wednesday: 21 - 28, light rain easing
Thursday: 19 - 28, possible morning drizzle
Friday: 15 - 30, sunny
Saturday: 19 - 33, mostly sunny
Sunday: 21 - 33, sunny
Monday: 21 - 34, sunny