Heavy rain and strong easterlies are lashing the upper North Island, including the Bay of Plenty, today.

The MetService has issued a heavy rain watch for the Bay of Plenty. A warning is in place for the Coromandel region.

"A slow moving low north of New Zealand directs an unsettled and humid east to northeast flow over the northern areas, with embedded fronts expected to move over the upper North Island during Wednesday and Thursday," says a spokesperson for the weather organisation.

"Rain or showers are expected to affect parts of the North Island, with some regions receiving heavy rain.

"A Heavy Rain Warning is now in force for Coromandel range, while Watches are in place for eastern Northland, northern Auckland and western Bay of Plenty for Wednesday and early Thursday.

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

Heavy Rain Watch

Area: Eastern Northland south of Kawakawa, Auckland north of the Harbour Bridge including Great Barrier Island
Valid: 24 hours from 10am Wed 14 Dec to 10am Thu 15 Dec
Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria, mainly about the higher ground.

Area: Bay of Plenty west of Papamoa, mainly about the Kaimai Range
Valid: 30 hours from 1pm Wed 14 Dec to 7pm Thu 15 Dec
Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria about the Kaimai Range.

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: Coromandel Range
Valid: 24 hours from 12pm Wed 14 Dec to 12pm Thu 15 Dec
Forecast: Expect 100 to 140 mm of rain about the ranges, with lesser amounts near the coast. Peak rates of 10 to 15mm/h expected about the ranges.
Note: Heavy rain may continue about the ranges after midday Thursday and the Warning timing may be adjusted in the next issue.