Alice Capsey cleared the rope twice as she top-scored with 28 off 15 balls in an England innings replete with cameos, while Nat Sciver-Brunt belted Lea Tahuhu out of the ground with one monster hit.
New Zealand were unable to match their opponents and had been restricted to 42 for five after 6.4 overs when another downpour proved terminal.
Because enough overs had been bowled, England won by 23 runs under the Duckworth-Lewis-Stern method and they can guarantee a series win in Canterbury on Thursday.
Maia Bouchier set the tone for England with a six in the first over while she added another three fours in a sparky 23 off 15 deliveries before holing out although no momentum was lost thanks to Capsey.
The 19-year-old got off the mark with a four then launched Jess Kerr and Leigh Kasperek over the rope, either side of Sciver-Brunt munching Tahuhu for the biggest six of the match.
Heather Knight struck 15 off eight balls before Sophie Ecclestone made sure the hosts, who took between seven and 12 runs off every over, finished with a flourish as she cracked her lone delivery over long-on.
Lauren Bell justified her inclusion as England went with the extra seamer after selecting four spinners in their series-opening win at the Ageas Bowl by accounting for New Zealand captain Sophie Devine at the start of the chase.
Dragging her length back, Bell tucked up Devine for room and the opener's ill-judged pull was well caught low down by Capsey, who took another fine catch when Amelia Kerr clipped to midwicket.
Brooke Halliday thumped New Zealand's lone six after Sciver-Brunt spilled a catch over the boundary rope before she was lbw to Charlie Dean, who had two wickets in her lone over when Suzie Bates reverse swept to Sarah Glenn.
When Jess Kerr offered catching practice off Ecclestone, New Zealand had slipped to 32 for five before another shower brought a truncated finish.