This analysis was written in the immediate aftermath of the blackout. For more recent updates, please click here

Hard on the heels of a "near miss" in July when it narrowly averted widespread blackouts, South Australia was warned on Wednesday night to prepare for an extended loss of electricity in the wake of wild weather.

Described as a once in a 50-year storm, the statewide disruption prompted power companies to warn that users of medical equipment should prepare to use back-ups, and mobile phone users to conserve batteries.

"We are experiencing a state-wide outage which means we have no supply from the upstream transmission network," electricity distributor SA Power Networks told clients late Wednesday.