Floods, downed powerlines and upturned trampolines are expected to greet residents this morning after a fierce storm set to pass over the country last night.

The short, sharp storm was set to bring damaging strong winds to central New Zealand, snow to low levels in the south and heavy rain in most areas as it swept north.

Forecasters were warning people not to get caught out in the storm, which would arrive suddenly and leave in the same way.

Wellington residents last night were being warned to tie down trampolines as winds with gusts of up to 140km/h were due to barrel through the Cook Strait overnight, with gales as far north as Taranaki.

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Heavy rain would also arrive in the middle of the night for many areas.

"If you're an extremely heavy sleeper you might not notice it, otherwise you might want to wear some ear plugs," MetService meteorologist Tom Adams said.

The "fast-moving" weather event hit Fiordland yesterday around lunchtime and was expected to hit the lower North Island around 10pm.

The rain will be welcomed in the South Island, although Niwa said it won't be enough to alleviate the long-term dryness in the region.

Drivers were being warned to stay off the roads, with floods, slips, wind, snow and icy surfaces among the possible hazards. Some of the worst-hit areas would get snow and heavy, strong winds, Adams said.

"That's a recipe for trees blowing over, power lines falling down."

While the South Island was set to clear up this morning, the bad weather would come later further north, the MetService said.

The storm will be relatively mild when it arrives in Auckland but a brief burst of heavy rain is expected in time for the morning commute.

A severe weather watch is in place for Auckland north through till 11am, with rainfall intensity possibly reaching up to 35mm per hour. Gales are also expected but nowhere near the severity forecast elsewhere.

Once the worst of the rain is over it is expected to clear the upper North Island, and the day should end with sunshine. In the south snow was expected to fall as low as 300m in Fiordland overnight, while heavy rain warnings were in force for Westland, Fiordland, the headwaters of Canterbury and Otago Rivers and lakes.