A much more improved batting performance allowed the Barras to set a target of 244.
This was thanks largely to Sese Bau (44) and an unbeaten 76 from veteran all-rounder Mahuru Dai.
In their run chase, Hong Kong were at 3/170 in the 33rd over when the heavens opened up.
The downpour lasted for over an hour which forced the implementation of the Duckworth-Lewis method.
Hong Kong's new revised target was then set at 178 in 38 overs which they reached comfortably thanks to Hayat who hit the winning runs with a boundary.
Anshuman Rath was named Man of the Match, while Hayat claimed the Man-of-the-Series award.