Wellington is set for a wet end to the day (file picture). Photo: RNZ / Rebekah Parsons-King
Rain and cold are set to sweep in across the country, with drivers warned to check conditions before travelling on the South Island passes from Wednesday evening.
A low is forecast around the north of the South Island later on Wednesday.
There could be a period of heavy rain for Fiordland, Westland and North Canterbury, and strong southerlies on the Kaikōura Coast.
Cold air is expected to follow the rainy front.
Mōrena, Good Morning.
— MetService (@MetService) April 30, 2024
️Rain moves up the South Island today reaching across to the North Island this afternoon.
❄️Behind the rain, cold air pushes northwards bringing a cooler night and even some snow for the higher parts of the Arthurs, Lewis and Porters passes. pic.twitter.com/bdhaFbDggz
MetService meteorologist John Law said there would be a big mid-week change after high pressure at the start of the week, but things should improve over the next couple of days.
"But today [Wednesday] we've got those colder temperatures creeping up the country, the risk of some snowfall perhaps in the higher parts of the Kaikōura ranges ... the northern parts of Canterbury - so yeah a bit of a wet and windy start for those central parts of New Zealand."
The front which brings the wet weather is moving north-west, he said.
A heavy rain watch is in place from Wednesday 6pm until Thursday 5am for Kaikōura and Canterbury north of Amberley.
Anyone looking to travel across areas such as Arthur's Pass or Lewis Pass tonight should keep up to date with information from Waka Kotahi due to the possible snowfall, he said.
MetService has a road snowfall warning in place for Lewis Pass from 9pm Wednesday until 3am Thursday.
The swells in Cook Strait would also be likely pick up today, he said.
"With that south-westerly coming through, you know stronger winds as well, it will be more of an interesting journey should we put it that way, but I think it's going to be the case, hopefully that starts to clear away in a better improving story heading towards tomorrow."
The heaviest rainfall is expected to be in the Westland ranges on Wednesday with up to 25mm in an hour and there is a severe weather watch in place for the northern parts of Canterbury, he said.
"So the northern parts of Canterbury and Kaikōura ranges perhaps catching the heaviest rainfall from tonight."
In the North Island, Wellington and Wairarapa are set for a "wet end to the day" and "a wet and windy night Wednesday into Thursday".
Rain is forecast for Auckland and Hamilton later on Tuesday afternoon and into the evening, but it should clear quickly, he said.
More generally May is likely to be fairly cool and dry and dominated by south-westerly winds, Law said.
