Heavy rain warnings are in place for the Gisborne and Bay of Plenty regions with the worst of the downpour expected this morning.

MetService has extended its warnings for both regions until 9pm tonight.

MetService meteorologist Thapi Makgabutlane told Morning Report that there had been about 80mm of rain overnight in the Gisborne region.

"Going forward, the warnings do speak about 60-120mm [of rain] for places away from the ranges, however we would expect the highest of those rainfall amounts in the ranges ... [to be] about 150-250mm of rain."

Makgabutlane says even though the areas forecasted to receive the most rain are not heavily populated, it is where a lot of the rivers are.

For surrounding areas like the Coromandel Peninsula and the central Hawke's Bay area there were also heavy rain watches in place, Makgabutlane says.

"Even if a place is under watch, there is still that possibility of very heavy rain ... and possible impacts as well."

Tauranga is now included in the extended rain warning.

Bay of Plenty emergency management controller Cara Gordon told Morning Report no reports of slips coming through yet.

"We've had a bit of rain come through in the region overnight, but not at levels that has caused issues, Gordon says.

"But ... as the forecasters are saying, we're expecting the worst of the rain to come through today."

There's good news, however, from about mid-week.

Makgabutlane says this weather system will gradually be easing out.

"We can start expecting a proper easing from the latter part of Tuesday, and then Wednesday looks like a mostly dry day out in that region.

"For the rest of the country if people do check out our severe weather outlook, you'll see a lovely statement that says minimal risk for severe weather for the next five days."

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: Bay of Plenty about and west of Matata including Rotorua
Valid: 13 hours from 9am Mon 25 Sep to 10pm Mon 25 Sep
Forecast: Expect 70 to 100 mm of rain. Peak rates of 10 to 20 mm/h.

Area: Bay of Plenty east of Matata
Valid: 13 hours from 9am Mon 25 Sep to 10pm Mon 25 Sep
Forecast: Expect a further 100 to 150 mm about the ranges and 70 to 100 mm elsewhere. Peak rates of 10 to 20 mm/h, This is in addition to the 200 to 250 mm of rain about the ranges and 70 to 100 mm elsewhere which has accumulated in the last 24 hours.

Area: Gisborne/Tairawhiti north of Gisborne City
Valid: 14 hours from 9am Mon 25 Sep to 11pm Mon 25 Sep
Forecast: Expect a further 100 to 150 mm inland and 70 to 100 mm near the coast. Peak rates of 10 to 20 mm/h. This is in addition to the 200 to 280 mm of rain inland and 70 to 100 mm near the coast which has accumulated in the last 24 hours.

-RNZ.