A severe storm warning has been issued for the Sydney metropolitan area by the Bureau of Meteorology this afternoon.
Flash flooding is on the cards over the next few hours, with rain already bucketing down in Sydney's west.
The State Emergency Service has advised that people should stay away from creeks and storm drains, and not ride or drive through water that has accumulated on the roads.
Computers and devices should also be unplugged, and phones should not be used during storms.
If possible, pets should also be brought inside.