The National Institute of Water and Atmospheric Research (Niwa) said: “A vigorous sub-tropical jet stream will drive the development of a strong, slow-moving low later this week.
“This will coincide with an atmospheric ‘stop sign’ (blocking high pressure) east of NZ, likely leading to widespread rain, some heavy - and it may last a while.”
Law said heavier rainfall would affect areas in the upper North Island, including Bay of Plenty, Northland and Auckland.
“As we go in towards Friday, the area of low pressure adds a bit more circulation which could feed that wet weather into the eastern coast of the South Island into places like Canterbury and Otago.”
Law said the unusually warm temperatures won’t last when colder air pushes up through the South Island, bringing chillier nights.
“It’s back to what you would expect for June,” he said.
“We have been spoilt with some very unseasonable temperatures but it was a brief blip and we’ll be back to something much more familiar for this time of year.”
While New Zealand should expect heavy and widespread rain later in the week, Law said we are looking at a much better few days beforehand.
“Tuesday and Wednesday look pretty good, with much more settled weather.”
Road snow warnings are set to come into effect for Lindis Pass and Crown Range Rd from 10pm tonight until early tomorrow morning.
Between 1-3cm of snow is expected to fall to around 700 metres.
While between 5-10cm of snow is expected to fall to around 700 metres on Milford Rd for four hours from 9pm.
