A "two-pronged" weather event is forecast to hit the country this week, not long after rain and snow swept through New Zealand in a chilly winter storm just last week.
Despite temperatures remaining higher than last week, the first storm is looking to flow across the North Island bringing rain and potential flooding in some areas of the Central Plateau, with the second hurtling across the middle and lower South Island packing significant rain, wind and snow.
Some areas could see their average monthly rainfall amount in just 24-hours.
NIWA principal scientist Chris Brandolino told 1 NEWS the first storm is approaching from the opposite direction from last week's wild weather, meaning it will bring warm, moist air from the Tasman Sea.
Rain is predicted for fall from Thursday afternoon from the Bay of Plenty and Gisborne, right up to Northland, including a fall for Auckland.
The combination of heavy rain and warm temperatures could be an issue for the snowfall over Central Plateau, likely to melt by Thursday night.
"It may cause some localised flooding issues," Mr Brandolino said.
Wellington is set to see rain on Thursday night, with the storm bringing a mild day for the capital.
A new "pretty strong" storm is forecast to form Friday morning just off Banks Peninsula, which could be a "significant producer of wind and rain" for certain areas between Christchurch and Dunedin, with middle and upper Canterbury likely to bear the brunt of the heaviest rain and the strongest winds.
In a 24-hour period from 6am Friday, some areas will see the equivalent of a month's worth of rain.
"In Christchurch, typically about 60 to 65mm of rain will fall during July, and in Timaru and Oamaru 40-45mm of rain falls during a typical month of July. Some areas in that region will likely approach or exceed their monthly July amount in 24-hours."
Mr Brandolino said the high rainfall could elevate the risk of flooding and slips.
Exposed coastal areas from Banks Peninsula, possibly down to Oamaru could be "under the gun" with winds up to 100-120 kilometres per hour, which could cause power outages or produce damage in the area.
Despite the warmer storm temperatures, higher areas of the Southern Alps proper, possibly 500 metres and above, are at risk of heavy snow intensity of about 1-1.5m to occur over the 24-hour period.