Spectators were told to get out of their seats and seek shelter about an hour before the match was due to start as lightning strikes began to hit.
There were still lightning strikes and rain at the original start time of 4.15pm (WST).
The stadium's lights flickered numerous times as the electrical storm gathered intensity.
Under Cricket Australia safety rules, any time a lightning strike is observed within 10km of the venue, play isn't allowed to start for at least another 30 minutes.
Huge puddles formed on the Optus Stadium turf as more than 15mm of rain fell within the space of an hour.
Officials have announced play will start at 5.35pm WST (8.35pm AEDT), with each innings to go for 11 overs barring any further disruptions.
The Scorchers won the bat flip and elected to bowl.
The Sixers will be without Jafer Chohan (illness) and Sean Abbott (hamstring), but star Pakistan captain Babar Azam will make his BBL debut.
The Scorchers will unleash a powerful batting line-up featuring Mitch Marsh, Finn Allen, Cooper Connolly, Aaron Hardie and Ashton Turner.
SCORCHERS: Mitch Marsh, Finn Allen, Cooper Connolly, Aaron Hardie, Ashton Turner, Laurie Evans, Nick Hobson, Ashton Agar, Joel Paris, Brody Couch, Mahli Beardman
SIXERS: Babar Azam, Daniel Hughes, Josh Philippe, Moises Henriques, Lachlan Shaw, Jack Edwards, Ben Dwarshuis, Joel Davies, Charlie Stobo, Mitchell Perry, Todd Murphy
15°C