A rapidly deepening storm will track past NZ this weekend and grow into a serious storm over the Southern Ocean across Sunday and Monday, sending severe gales and cold winds back into NZ.

Northern NZ will be least affected by it – but even gales in the north are possible.

The South Island and central part of NZ (around Cook Strait) look to be most impacted by the winds and colder air.

We take a detailed look at this low, which should reach criteria to be classed as a ‘weather bomb’ (bombogenesis) – when air pressure falls more than 24hPa in 24 hours.