UDPATE 3.19PM: A new rain warning has been issued for the Bay of Plenty.

A severe weather watch was issued earlier today, but this has now been upgraded to a warning.

Heavy rain is forecast for parts of northern and central New Zealand. Possible severe gale northeasterlies for northern North Island

"In this issue Northland, Auckland north of Orewa, and Coromandel Peninsula have been upgraded to a red heavy rain warning," says a MetService spokesperson.

"This decision is based on collaboration with local authorities and on concerns for significant impact that further heavy rainfall on these saturated catchments may cause.

"Meanwhile, Bay of Plenty has been upgraded to an orange heavy rain warning.

"A strong and humid northeast flow covers northern and central New Zealand, with bursts of heavy rain and thunderstorms likely for a number of regions through into Wednesday.

"A number of warnings and watches remain in force for heavy rain and possible severe northeast gales.

"People are advised to keep up to date with the latest forecasts in case any changes are made, or further areas are added."

Heavy Rain Warning - Red
This rain is expected to cause dangerous river conditions and significant flooding. Slips and floodwaters are likely to disrupt travel, making some roads impassable and possibly isolating communities.

Area: Northland
Valid: 24 hours from 4am Tue 31 Jan to 4am Wed 1 Feb
Forecast: Expect 100 to 140 mm of rain in the north and east, with lesser amounts in the west. However, localised areas may receive 140 to 220 mm. Peak rates of 10 to 20 mm/h, mainly in the north and east, but localised areas may see 25 to 40 mm/h, or possibly more. Thunderstorms are also possible, and a Severe Thunderstorm Watch is also in force.

Area: Auckland north of Orewa
Valid: 12 hours from 5pm Tue 31 Jan to 5am Wed 1 Feb
Forecast: Expect 80 to 120 mm of rain. Peak rates of 10 to 20 mm/h, but localised areas may see downpours of 25 to 40 mm/h. Thunderstorms are also possible.

Area: Coromandel Peninsula
Valid: 18 hours from 12am Wed 1 Feb to 6pm Wed 1 Feb
Forecast: Expect 80 to 120 mm of rain about the ranges, with lesser amounts about the coast. Peak rates of 15 to 25 mm/h, mainly about the ranges.

Heavy Rain Warning - Orange
Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

Area: Auckland from Orewa southwards, and Great Barrier Island
Valid: 12 hours from 6pm Tue 31 Jan to 6am Wed 1 Feb
Forecast: Expect 50 to 80 mm of rain, especially north of the Harbour Bridge. Peak rates of 10 to 20 mm/h, but localised areas in the north may see downpours of 25 to 40 mm/h. Thunderstorms are also possible.

Area: Bay of Plenty
Valid: 21 hours from 6am Wed 1 Feb to 3am Thu 2 Feb
Forecast: Expect 90 to 140 mm of rain, with the largest amounts likely about inland areas west of Whakatane. Peak rates of 15 to 25 mm/h.

EARLIER 2PM:

MetService has issued a fresh batch of Severe Weather Warnings for regions recently affected by extreme rain.

The moisture lingers through the week and even spreads across the South Island.

Heavy rain with the potential for thunderstorms and downpours returns to northern areas early on Tuesday and will continue into Wednesday.

'The very warm and humid airmass covering Aotearoa brings ripe conditions for persistent, heavy rain plus the risk of thunderstorms which can further intensify the rainfall,” says MetService meteorologist Lewis Ferris.

Localised parts of Northland (especially north of Whangārei) could see in excess of 200mm of rain fall in around 24 hours which, given the already sodden ground, could bring about flooding quickly.

Parts of Auckland could see a further 100mm or more and people should be preparing for further rain related impacts from late on Tuesday into Wednesday.

Coromandel Peninsula is also in the firing line with this next event, and the Heavy Rain Watch currently in force is expected to be upgraded to a Warning later today (Monday) as forecast rain is likely to bring about further slips midweek.

Wednesday through Friday could see further rain accumulate around northern regions, but current information is suggesting this rain will be less heavy and not as widespread.

Please follow advice from local authorities.

Heavy rain shifts to the Coromandel and Bay of Plenty on Wednesday and parts of the South Island will also receive some moisture.

Western areas of the South Island are running a lot drier than normal (20-50 per cent of January normal) but look to get a string of rainy days from midweek into the weekend.

This may come as welcome news but there's the potential of heavy rain in the mix too.

'Nationwide we're in for a week of steamy temperatures which will be notably warm overnight. New Plymouth Airport only got down to 20.2°C Monday morning, making it one of its warmest January nights,” says Lewis.

'On a more positive note current information suggests the upper North Island will have some settled weather for Waitangi weekend.”

Given northern areas of New Zealand have already experienced record-breaking rainfall this month it is more important than ever to keep up with the latest forecasts.