Watch for flooding: Warnings issued throughout country

It's a wet day across the country with rain expected for all of New Zealand and a severe thunderstorm watch for people in most of the North Island and the top of the South Island.

MetService said heavy rain is already hitting Nelson, Buller and Westland and a second rain band is expected to affect western regions of the North Island from this afternoon.

Heavy rain brings flooding to Portland Road in Remuera at lunchtime today. Photo / Connor Haythorne

A severe thunderstorm watch is in place for Northland, Auckland, Coromandel Peninsula, Waikato, Waitomo, Taumarunui, Taupo, Taranaki, Taihape, Whanganui, Manawatu, Tararua, Kapiti-Horowhenua, Nelson and Buller.

"A low pressure system over the Tasman Sea directs a moist northerly flow across New Zealand, and is forecast to move slowly eastwards during today and Monday. Expect widespread rain across the North Island and the upper South Island during this period," MetService said.

The heaviest rain is expected about Westland from Fox Glacier northwards, Buller, Nelson, Marlborough, western Taranaki, Tongariro National Park, Taupo, Rotorua, Bay of Plenty, Waikato from Morrinsville eastwards, Coromandel Peninsula and Great Barrier Island.

Rainfall of 160mm to 200mm is expected to accumulate about the Kaimai Ranges and Tongariro National Park tonight and tomorrow.

Parts of Waikato, Bay of Plenty, Rotorua, Taupo, Great Barrier Island and Coromandel Peninsula could expect 110mm to 160mm over the same period.

MetService said 20mm to 30mm could fall per hour.

Motorists are urged to take care as heavy rain brings surface flooding. Photo / Connor Haythorne

Nelson could expect a further 100mm to 150mm on top of what has already fallen about the ranges west of Motueka, and 60 to 100mm elsewhere today and tonight.

Rain will affect ALL of NZ at some point today. Heavy rain is already affecting Nelson, Buller & Westland with a second band expected to affect western regions of the North Island from afternoon. Keep updated with the rain radar & watched/warnings at https://t.co/hnwmGxU1gR ^AC pic.twitter.com/T2TlojBuQG

— MetService (@MetService) February 10, 2018

Niwa is warning people to be watch out for flooding from the intense downpours.

Steams rising fast in #Auckland area. This one in Browns Bay already approaching the top of cement banks. ~Chris

— NIWA Weather (@NiwaWeather) February 10, 2018

Niwa said global models indicated heavy rainfall of 100mm for parts of the North Island including Bay of Plenty, Waikato, Auckland and Northland and in the upper South Island.

When global model & its ensemble mean (in this case avg of 51 outcomes) indicates heavy rainfall, it inc confidence it'll happen. 100+ mm good bet from BoP to Waiktao to AKL & Northland regions (not necessarily all locations within zone) & upper SI. Need to watch for flooding. pic.twitter.com/uISEYYdmmq

— NIWA Weather (@NiwaWeather) February 10, 2018