Mair brought about an early lunch after dismissing the entire Wanganui tail in the course of two overs and restricting the home side to 135 runs.
Wanganui set another attacking field and were well rewarded with two early wickets from catches in close off the bowling of Watkin (2-28).
However, Mair (66 not out) proved to be just as handy with the bat as the ball - partnering with Sophie Pyott (34no) to steer Hawkes Bay home in just 21.5 overs.
It was a despondent Wanganui side who walked off the field, which coach Dilan Raj saw as a positive.
"It shows we care.
"We knew it was going to be hard out there without Michelle and Lucy and all agreed pre-match that we needed to put in another 10 per cent to compensate.
"We struggled to find our length with the ball this week, and lost a few wickets too easily while batting.
"We know we have a lot of work to do before our next match, but we've got time on our side."
Wanganui now head into a three-week break, before facing Manawatu at Victoria Park on December 10, while they will have the bye in the final round in January.