Southern defended well at times but Alhambra-Union dominated possession, and with Olivia Waldron kicking conversions, the score crept up.
Jess Hannan-Brennan won most of the lineout ball jumping at two, and regular loose forward Rachel Scott, playing at centre, ran strongly and was rewarded with a try.
Surprisingly, given the very wet conditions, both teams handled well in the first half but this aspect did deteriorate in the second half when the rain resumed.
Southern actually dominated the first 15 minutes of the second half but, as the game moved on, the home team regained the upper hand.
Alhambra-Union loose forwards Kerry Stoddart, Megan Kane and Nicky Crawford all scored tries, and second five-eighth Courtney Martin scored two. Other try-scorers were Lorralea Tekoi, Georgie Anderson and Joslyne Umpherville.
For Southern, Meghan Roberts and Mikayla Sheck were relentless in their tackling, and Verina Wihongi was the best of the backs, showing good defence out wide to stop some Alhambra-Union breaks.
University also shrugged off the wet, scoring 14 tries in a 78-10 win over Kaikorai at the University Oval.
Prop Kelly Whitten had her best game for the season for the students and was supported by fellow front-rowers Molly Wright and Sophie Kuper.
University had too much skill and pace in support for Kaikorai to really threaten. Kaikorai was plucky but outmatched, requiring assistance to make up team numbers. Lucy Andersen reached 25 tries for the season for the students.
Pirates beat Blues 63-5 in Invercargill.
