An "intense burst" of rain, snow, lightning and powerful winds are set to "thrash" the country on Monday and Tuesday, NIWA says.
Rain and possible thunderstorms will cover most of the country but clear by late Monday night.
MetService has issued heavy rain and wind warnings for Wellington, parts of Taranaki, Whanganui, Westland and Canterbury.
They are a result of a low that formed on Friday in the Southern Ocean west of Aotearoa.
Taranaki will be the wettest place, with up to 100mm of rain forecast to fall before 7pm - heaviest in the afternoon and evening.
Snow is also forecast to fall across the country, with a heavy snow watch in place for areas above 800m in Central Otago northwest of Alexandra, including the Queenstown Lakes and Mackenzie Basin.
The SnowNZ skifield forecast shows Cardrona and Treble Cone are set to receive 39cm of snow over the next 48 hours. Coronet Peak and The Remarkables will get 25cm.
Weather warnings in place for July 1
Heavy Rain Warning - Orange
Area: Mount Taranaki/Taranaki Maunga
Period: 9hrs from 10am - 7pm Mon, 1 Jul
Forecast: Expect 70 to 100 mm of rain. Peak intensities of 15 to 20 mm/h Monday afternoon and evening. Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.
Area: The ranges of the Westland District
Period: 6hrs from 9am - 3pm Mon, 1 Jul
Forecast: Expect 60 to 80 mm of rain to accumulate on top of what has already fallen. Peak rates of 15 to 20 mm/h. Rain easing from the south. Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.
Area: The headwaters of the Canterbury lakes and rivers south of Arthur's Pass
Period: 4hrs from 9am - 1pm Mon, 1 Jul
Forecast: Expect 50 to 70 mm of rain about the main divide, and 30 to 50 mm of rain within 15km east of the main divide on top of what has already fallen. Note, further rain likely during Monday afternoon, but this is likely to fall as snow on the ranges. Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.
Strong Wind Warning - Orange
Area: South Taranaki, Taihape and inland Whanganui
Period: 6hrs from noon - 6pm Mon, 1 Jul
Forecast: Severe gale northerly winds gusting 120 km/h in exposed places. Minimal chance of upgrading to a Red Warning.
Impact: Damage to trees, powerlines, and unsecured structures possible. Driving may be difficult, especially for high-sided vehicles and motorcycles.
Action: Prepare your property by securing items that can be picked up by strong winds. Drive cautiously.
Area: Wellington
Period: 7hrs from 11am - 6pm Mon, 1 Jul
Forecast: Severe gale northerly winds gusting 120 km/h in exposed places. Minimal chance of upgrading to a Red Warning.
Impact: Damage to trees, powerlines, and unsecured structures possible. Driving may be difficult, especially for high-sided vehicles and motorcycles.
Action: Prepare your property by securing items that can be picked up by strong winds. Drive cautiously.
Heavy Rain Watch
Area: Buller District, and Tasman west of Motueka
Period: 6hrs from 9am - 3pm Mon, 1 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Area: The Tararua Range
Period: 7hrs from noon - 7pm Mon, 1 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Area: The eastern ranges of Bay of Plenty and the inland ranges of Gisborne
Period: 8hrs from 7pm Mon, 1 Jul - 3am Tue, 2 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Heavy Snow Watch
Area: Central Otago northwest of Alexandra including the Queenstown Lakes, also the MacKenzie Basin
Period: 6hrs from 9am - 3pm Mon, 1 Jul
Forecast: A period of heavy snow above 800 metres, where snowfall amounts may approach warning criteria. Low chance of upgrading to a Warning.
Strong Wind Watch
Area: Inland and northern parts of Marlborough
Period: 6hrs from 11am - 5pm Mon, 1 Jul
Forecast: Northwest winds may approach severe gale in exposed places. Low chance of upgrading to a Warning.
Area: Wairarapa south of Carterton
Period: 6hrs from 1pm - 7pm Mon, 1 Jul
Forecast: Northwest winds may approach severe gale in exposed places. Low chance of upgrading to a Warning.
Area: Canterbury High Country
Period: 4hrs from 9am - 1pm Mon, 1 Jul
Forecast: Northwest winds may approach severe gale in exposed places. Low chance of upgrading to a Warning.
