Rain is being forecast for the next few days as a deepening low over the north Tasman Sea moves slowly eastwards.

The MetService expects the low to weaken as it passes north of New Zealand during the weekend.

Heavy rain is forecast for the region as a deepening low moves over the country. File photo.

'A strong, moist northeast flow ahead of the low is forecast to bring periods of rain to northern New Zealand from Friday through to early Sunday,” says a statement from the weather organisation.

'Some heavy falls are likely about Northland, Auckland, Coromandel Peninsula, western Bay of Plenty and eastern Waikato during this time.”

The MetService has issued a severe weather watch for the Bay of Plenty and Coromandel regions.

'In the Coromandel, rain is expected to become heavy at times from mid-afternoon Friday through to Saturday night or early Sunday. Rainfall amounts here may well exceed 100mm in places during this time, especially about the ranges.”

In the BOP, west of Te Puke and eastern Waikato near the Kaimai Range, rain is expected to become heavy at times early evening Friday through to late Saturday.

'Rainfall amounts could approach warning criteria during this time, especially about the Kaimai Range.

'MetService forecasters will continue to monitor the situation and advise people in these areas to remain up to date with the latest forecasts in case parts of this watch are upgraded to a full warning.”