Cronulla ran with the wind in the first half, opening the scoring through Michael Gordon in the seventh minute, before Luke Lewis added to that in the 23rd minute.
Alex Johnston replied for the visitors in the 31st minute.
A Valentine Holmes penalty put the home side further ahead after halftime before Chris McQueen dived onto a Luke Keary kick to bring Souths back into the contest in the 54th minute.
But Souths couldn't go on with it and consistently struggled to work the ball out of their own end against some punishing Sharks defence.
Before a hardy 3978 fans, Bukuya put the Sharks out to an eight point lead late and they held off Souths bravely in the final stages to secure a deserved win.
Sharks coach Shane Flanagan praised the spirit of his side in the incredible conditions.
"I have never seen anything like it, the wind, the rain, they were extreme conditions," he said.
"I thought it was an outstanding game from both sides, we were up at 90 per cent completion rates, Souths were at 82.
"And from one to 17 we were outstanding.
"That second half was our best for the year and if you look back it is probably the best for a couple of years.
"I know we are capable of doing that week in week out."
Coach Michael Maguire said Souths lost the "key moments".
"We played against a good team and they completed on every play," he said.
"We allowed them to find field position (often) and they took advantage of that.
"We had opportunities throughout to win that game."
Both Flanagan and Maguire said they never considered abandoning the fixture because of the conditions.
- AAP
