MetService is forecasting heavy rain for many parts of the country this week as weather systems coming from the north bring moisture laden air to New Zealand.

A feed of subtropical air is producing heavy rain over Coromandel Peninsula and the Bay of Plenty today. This band of rain is expected to move eastwards over northern Tairāwhiti/Gisborne tonight before moving back towards the west tomorrow night.

Severe Weather Watches and Warnings have been issued for these areas.

The low pressure that is bringing the wet weather is also dragging warm air across the country with many places in for an exceptionally mild start to May.

A stubborn area of high pressure to the east of the country acts as a block to the progression of weather features across New Zealand - leading to some slow-moving areas of heavy rain later this week.

Since Sunday morning until midday today, 278mm of rain has been recorded at Pinnacles Hut in the Coromandel Range, with lesser amounts along the coast (59mm at Whitianga Airport).

The highest amount recorded in Northland during this time was at Kaikohe with 227mm, while several other stations recorded 100-150mm. Meanwhile, 40-50mm of rain fell across Auckland city.

Though the wet weather in Auckland and Northland through the weekend has eased, there is the risk of another period of heavy rain in these areas from Wednesday, which may affect the Coromandel as well.

'MetService is keeping a close eye on this rain band, but there is still some uncertainty surrounding the details of when and where the heaviest rain will fall later this week. Kiwis should keep an eye on updates to the MetService Severe Weather Warnings as the situation evolves,” says MetService meteorologist Dan Corrigan.

Looking further south, the West Coast and northwestern Tasman can expect bursts of heavy rain throughout the week as low pressure systems roll in from the Tasman Sea. Orange Heavy Rain Warnings and Watches are in place, as well as a Strong Wind Watch for northeasterly winds affecting southern Westland tomorrow. In comparison, the east of the South Island from Canterbury southwards will have mostly dry and settled weather this week.

Temperatures this week are well above average for the start of May.

Across the North Island, temperatures are expected to stay in the high teens overnight throughout the week.

'Many places across both islands will have overnight temperatures more than 6 degrees warmer than usual, so the extra blankets might need to go back in the cupboard for a while," says Dan.

From Wednesday through to Saturday, an unsettled northerly flow affects New Zealand with several embedded fronts bringing rain to northern and western parts of both islands. A period of northerly gales are also likely in exposed places.

For Fiordland, Westland and Buller, there is high confidence rainfall amounts will reach warning criteria on Wednesday, especially about the ranges.

For western Tasman, there is moderate confidence of warnable amounts of rain from Wednesday to Saturday.

For the remainder of Tasman including the Nelson region, also northern Marlborough, there is low confidence of heavy rain on Wednesday but high confidence on Thursday, Friday and Saturday.

For Horowhenua to Wellington including the Tararua Range, there is moderate confidence rainfall amounts will reach warning criteria on Thursday and Friday.

For Northland and North Taranaki, there is moderate confidence of warnable amounts of rain from Wednesday to Friday, reducing to low on Saturday.

Finally, for Auckland, Waikato, Waitomo, the central high country, Coromandel Peninsula, Bay of Plenty and the far north of Gisborne, there is moderate confidence of heavy rain on Wednesday and low confidence on Thursday.