Civil Defence is warning Aucklanders that "high-intensity rainfall" and thunderstorms will whip through the city today.
They want residents to clear any gutters and drains and be prepared for large amounts of rain while driving.
Near Wellington, the New Zealand Transport Agency is having to close roads due to flooding.
In a tweet just after 11.30am today, it states State Highway 53 Waitenga Bridge in Martinborough is currently closed.
The Carterton District Council has also announced Millars Rd is closed, along with Stronvar Rd, Masterton, and Whiterock Rd at Lagoon Hills Rd.
In south Wairarapa, the Haungarau Bridge on Ponatahi Rd was closed due to flooding. The Pararaki River and the Managetoetoe Ford on Cape Palliser Rd were also flooded.
Meanwhile, Weatherwatch.co.nz says although it was too early to confirm, the bout of bad weather could impact any Christmas parades scheduled for this weekend.
"Unfortunately, this weekend will see more showers/downpours which may impact Christmas parades and other outdoor events - but nothing is yet locked in for the weekend weatherwise as we still need a couple more days to be sure of where the showers/downpours are most likely to appear."
However, some areas would still bask in dry, warm weather.
November would be ending as December begins with rain forecast for both islands.
"WeatherWatch.co.nz says despite other forecasters warning of dry conditions many farmers and growers across New Zealand will be very pleased with recent rain especially now with the forecast of plenty of warm northerlies and increasing dry spells (among the downpours) as we head into December, which bodes well for rapid pasture and plant growth."
The MetService earlier told the Herald a rain watch was in place for Canterbury north of the Waimakariri River.
Looking ahead, a complex low-pressure system with a number of low centres and associated troughs would move to the east on Wednesday followed by a brief ridge of high pressure on Thursday.
There was a chance rain would reach warning criteria in the east from Gisborne to northern Canterbury on Wednesday.
"Another complex low-pressure system should move on to the country from the north Tasman sea during Friday and Saturday, bringing rain and strong northeast winds to many places of the country," MetService said.
"In addition, there is low confidence of northeasterly winds approaching severe gale strength in exposed places of Northland, Auckland, Coromandel Peninsula, Waikato and Waitomo late Friday and Saturday."
Rain could reach warning amounts in Northland, Auckland, Coromandel Peninsula, Waikato and Waitomo on late Friday and Saturday.