For the Blues South, it's now five wins in seven games after they reaped revenge against the Ospreys at Taffs Well.
Having lost 31-7 at Llandarcy back in September, the South crossed for three first half tries before holding on after the interval to secure a 24-18 success.
Both games were dominated by high winds and heavy rain on a night when running rugby was almost impossible. However, as Blues South team manager John Richards said; "It was like a mud-bath, but both teams have to take credit for the manner in which they tried to play.
"They did their best to play, but in the end it was down to who was the stronger. Thankfully, we held on for what was a well deserved and very important win."
With the wind and rain at their backs, the South raced into a 24-0 interval lead courtesy of tries from Zak Deere, Ruraigh Smith and Jack Phillips. Gareth Thompson improved his points haul for the season with three conversions and a penalty.
It was all change after the interval with the Ospreys pinning the Blues back in their own 22 for long periods. Rhys Williams, Evan Yardley and Nicky Smith all went over for tries with Ben Thomas adding a penalty late on to make sure of a losing bonus point.
In the other game, the North were 14-10 winners against the Dragons at the Recreation Ground.
North team manager Nigel Way said; "It was an awful night in terms of the weather and all credit has to go to both sides for producing such an entertaining game.
"I'm pleased with the way we battled and that we are developing nicely after a difficult start to the season."
A penalty from Niall Martin on 26 minutes put the Dragons in front, but by half time, the North had stolen the advantage courtesy of a penalty try, a try from James Parry and two conversions from James Dixon.
Scott Matthews crossed eight minutes from time for Ethan Davies to convert, but despite pressing hard in the final moments, the hosts were unable to break down a resolute North side who were fully deserving of their first away win of the season.