MetService issued a heavy rain watch alert in the area shortly before 8am and is not due to lift until about 9pm.
"A period of heavy rain and thunderstorms [are] possible. Rainfall amounts may approach warning criteria," the alert said.
Other rainy parts of the country include Dunedin, with 33mm, and Ashburton, with 46mm.
Aucklanders are waking up to a chilly morning, with a temperature of 11.5C, feeling like "three layers of clothing", recorded just before 8.30am.
MetService said that rain may become heavy at times and there is also a possibility of thunderstorms and strong northwesterly gusts.
A temperature high of 16C and an overnight low of 9C is forecast in the City of Sails.
Meteorologist Andy Best said forecasted temperatures around the country are expected to be in line with the historical average, but wind chill in some places would make it seem colder.
Places away from wind could expect frost in the morning tomorrow.
The rain comes after a horrendous weekend of wild weather for parts of Auckland, particularly in and around East Tāmaki, Papatoetoe and Otara.
A tornado ripped through parts of South Auckland on Saturday - so strong that it lifted roofs off, tore through business buildings and sent trampolines flying.
It also ripped up trees and fences; and even sent a shed flying into an ambulance where a pregnant woman was in labour in Otara.
The woman's baby boy still did not have a name as of yesterday, but the couple were thinking of the moniker "Storm" as a fitting tribute to his entry into the world.
Northland to Taranaki, including the Bay of Plenty and the central high country, are all in for showers that will become more frequent this morning and later this afternoon.
And like Auckland, those conditions may turn to heavy rain, thunderstorms and even hail.
READ MORE:
• 'Terrifying tornado': Flooding and roofs lifted in Auckland wild weather
• Auckland tornado terror: 'Everything was destroyed, absolutely everything'; weather expected to now settle
• Wild weather: Severe thunderstorm warning as rain hits Auckland, top of the North Island
• NZ's cold weather explained: What's created this weekend's monster high?
Gisborne is one of the better places to be today, as sunny weather is due the whole day.
The only other place in the country to get a near-perfect day is Westport, which is in for a mainly fine Monday - save for the chance of a spot of rain late this morning.
People in around Whanganui, Wellington and the Wairarapa will see a few showers. Those are due to turn into rain later.
Road snowfall warnings
In the South Island, MetService has also issued road snowfall warnings for a number of main roads in the South Island.
Lewis Pass (State Highway 7) is expected to get a period of snow showers from about 9am to 2pm today. Up to 2cm of snow may accumulate on the road near the summit - with lesser amounts to 600m.
Snow showers are also due over Arthur's Pass (SH73) from now until about 10am. That area is expected to get anything from about 3cm to 6cm of snow near the summit.
Anyone driving on Porters Pass (SH73) is being told that between 8cm to 15cm of snow may build up near the summit also.
Authorities are due to give an update on road snowfall warnings at 11am.
Scattered rain is forecast for areas including Nelson, Buller and Westland before clearing by this afternoon.
In Marlborough, rain is due to develop with snow above 700m this morning.
Those in Canterbury are in for rain north of Timaru before easing to become scattered showers throughout the morning.
Fine conditions are on the cards for western Fiordland while scattered showers are expected in Otago and Southland.
