A severe weather warning for heavy rain is being issued for the Bay of Plenty and Rotorua.

Heavy rain is expected to hit the region from about 3am Friday, warns the MetService.

A front preceded by a moist northerly flow is expected to move slowly east across New Zealand today and Friday bringing rain to much of New Zealand, says a spokesperson for the weather organisation.

"The heaviest rain is likely to affect the north of the North Island, and the north and west of the South Island.
Localised downpours and thunderstorms are also possible for northern regions of the North Island.

"Watches for heavy rain are in force, and rain warnings have now been issued for Bay of Plenty including Rotorua, and the Tasman District.

"People are advised to keep up to date with the latest forecasts."

Image: MetService.

Heavy Rain Warning - Orange

Area: Bay of Plenty and Rotorua
Period: 17 hours from 3am Fri 14 Jun to 8pm Fri 14 Jun
Forecast: Expect 80 to 110 mm of rain to accumulate. Peak rates of 15 to 25 mm/h, but rates of 25 to 35 mm/h possible in localised downpours and thunderstorms.
Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.

Meanwhile, a heavy rain watch is in place for the Coromandel Peninsula and Taupo.

In the 18 hours from 8pm Thursday to 2pm Friday, people in the Coromandel region can expect periods of heavy rain, says the MetService.

"Amounts my approach warnning critieria. Thunderstorms are possible."

In Taupo, periods of heavy rain are expected in the 15 hours from 6am Friday to 9pm Friday.