Brisbane Heat had the momentum but failed to make it count when it really mattered.
They were just one win from the final after four victories in a row, but sadly it all went haywire at the Manuka Oval.
After sending the Scorchers to bat first, the Heat gave away needless runs through sloppy fielding, wayward bowling and a liberal dose of panic.
In the process, they allowed Scorchers to post a mammoth 1-189 from 18.1 overs.
The Canberra rain intervened leaving the Heat with 200 runs to chase from 18 overs under the Duckworth-Lewis-Stern method.
It was a no contest as the the Heat finished at 150 for 9 wickets.
As a result, Perth meet Sydney Sixers who are the reigning champions. Perth themselves have won the championship three times in the past.
Jason Behrendorff (2-19 off three) made the difference for Perth, getting Lynn and opening partner Joe Denly (14 off 7) out in consecutive balls to put the brakes.
For the Scorchers, Liam Livingstone (77 off 39) blasted 11 boundaries and was well supported by makeshift opener Cam Bancroft (59 off 42) resulting in a 114-run opening stand.
The Scorchers suffered a jolt before the game when their key player, Jason Roy suffered an ankle injury.
But Bancroft filled in beautifully and played a vital role in helping Perth to a big score.
Mitch Marsh (49 not out in 28 balls) ensured there was no let up in the fireworks show. In fact, Bancroft and Marsh posted 62 runs in the last 25 balls before the rain started.
The big disappointment for the Heat was South African Morne Morkel who gave away 45 in just 4 overs.
Marnus Labuschagne (0-36 off two) was man of the match last time the two sides met but had a forgettable outing. Livingstone tore into his bowling blasting 27 runs off his 10th over.
He failed with the bat too, falling cheaply to spinner Fawad Ahmed who was impressive with 2 wickets for just 26 runs.
The Heat will also regret leaving out their top wicket taker Mark Steketee in place of Morkel who had a nightmare of a match.
Perth Scorchers 189 for 1 (Livingstone 77, Swepson 1-26) beat Brisbane Heat 150 for 9 (Burns 38, Hardie 3-46) by 49 runs (DLS method)