Cairns has been recuperating from a knee injury in recent months and withdrew from Southern's first match of the series last week.
However, he appeared in two Shell Super league Max matches last week, coming through those and an intensive workout mid-week satisfactorily.
Cairns said he feels confident of taking a full part in the Southern side.
``I was still a bit short of a gallop last week but the workouts I did last week have proved I'm ready to go again,''Cairns said.
Cairns's inclusion will further bolster an already strong Southern side, which opened the series with a convincing nine-wicket win over Central, at Lincoln Green on Saturday.
Cairns will replace Mark Richardson in the Southern side, who was called in initially to cover for the Canterbury all-rounder.
Southern Conference coach Warren Lees said it was likely that, apart from Cairns coming back, another pace bowler, Warren Wisneski, 12th man against Central, would play, while one of the left-arm pace bowlers, either Geoff Allott or Shayne O'Connor, would be rested.
``It's good if we can get into the position of being able to rotate the quicker bowlers,'' Lees said.
He said Southern coped well with only two specialist seamers against Central with Nathan Astle filling the third seamer's position capably.
``I was pretty happy over all with how things went but people are saying we are strongest side on paper and should do well.''
Lees said he was impressed with the bowlers contributions in dismissing Central twice for two modest scores on a wicket renowned as favouring the batsmen.
``It was good for the bowlers like Allott and O'Connor to show that they need not be frightened of a good track. Provided they get good pace and rhythm and do a bit with the ball they can get wickets. It's the same for the slower bowlers.''
Lees said because of the nature of the wicket batsmen's eyes tend to light up expecting a big score, but the hard work still has to be done. Only Chris Harris and Matt Horne of the Southern side passed 50. Lees said he was taking a low-key approach with the Southern side with the amount of cricket on this season.
``It's about switching on when you have to and then off again.''
Central captain Craig McMillan was in no doubt where his team had let themselves down.
``Scoring 300 as we did in the first innings and only 230 in the second is not enough on this wicket -- 400 runs is really the minimum.
``Once you get in it should be hard to get out. If the bowlers are just a little off target they will get punished.''
The other match starting today pits Northern against Central at Rangiora's Dudley Park. Central wicketkeeper Robbie Hart, who was injured on the second day of the game against Southern, is fit to play, while in the Northern squad Adam Parore replaces Chris Nevin.