The conditions in Pukekohe were greeted with glee by some kids in the crowd, who spent much of the match throwing themselves down a lengthy mudslide fashioned on the banks, but they hardly conducive to running rugby.
The first half barely featured a line break as both sides wisely opted to keep it tight, with Counties gradually taking command of possession and finding reward. Having opted three times to kick for the corner rather than take the three points on offer, openside flanker Fotu Lokotui soon made that decision a wise one by crashing over after an effective lineout drive.
But Auckland hit back when Steelers No 8 Sam Henwood was sent to the sin bin for a big hit on Jordan Trainor, with Jono Hickey cleverly planting the ball against the posts while the visitors were enjoying numerical ascendancy.
Counties were unable to add to their solitary try even after being restored to their full complement, being doomed throughout by committing too many turnovers and making too many handling errors.
And Auckland eventually made their hosts pay for their mistakes, with Malakai Fekitoa finishing off the best move of the match after Dan Bowden dropped a fine grubber behind the opposition defence.
Fortunately for the mud-covered fans watching on, Kerr soon settled the result in impressive style, allowing Counties to open their campaign with a win ahead of next weekend's trip to Waikato. Auckland, meanwhile, will be confident of bouncing back when they host Northland.
Counties Manukau 16 (F. Lokotui try; B. Kerr con, 3 pens)
Auckland 14 (J. Hickey, M. Fekitoa tries; J. Hickey 2 cons)
Halftime: 10-7