Weather: Bay of Plenty braces for heavy rain amid tropical July-September outlook

An orange heavy rain warning is in place for the Bay of Plenty tomorrow, with risk of surface flooding and slips.

MetService warned areas west of Whakatāne could get up to 120mm of rain from 10am today to 3am tomorrow, with those east of Whakatāne expecting up to 130mm between 12pm and 10am, and 150 to 200mm in some areas.

The MetService warning is in force until 3am Friday and is due to be reviewed tonight.

Strong wind and heavy rain watches were also in place for Auckland, Northland and Coromandel tomorrow.

Regional duty civil defence controller Stace Tahere said it had not been long since the last heavy rain so the ground may still be sodden.

People were encouraged to clear their drains and gutters, and be aware of potential surface flooding, slips and difficult driving conditions.

“If there is surface flooding in your area and you see rising water, do not wait for official warnings. Head for higher ground.”

The Bay of Plenty Regional Council Flood Room has been shifted to an active watch status as a precaution.

Flooding along Welcome Bay Rd last Friday.

A duty flood manager said water would be spilled from the Matahina Dam due to significant recent rain in the Rangitāiki catchment, and stock on low-lying ground beside the Rangitāiki River should be moved higher.

“This warning does not apply to areas protected by stopbanks … there is no risk of flooding in Edgecumbe or the Rangitāiki Plains area.”

Rotorua Lakes Council said there was potential for surface flooding and rising waterways and encouraged residents to clear drains and gutters and drive cautiously, especially in low-lying areas.

The planned closure of the State Highway 2 Pekatahi Bridge on Thursday for deck repair work has been postponed until Friday, weather permitting, NZ Transport Agency said.

The resurfacing work will now take place on Monday.

Earth Sciences New Zealand meteorologist Chris Brandolino said an atmospheric river that stretched up to sub-tropical New Caledonia would sweep over much of the North Island and the top of the South Island in the coming days.

People may want to do outdoor activities with their children during the school holidays, but “I would avoid that for much of the country, upper South Island, much of the North Island”, Brandolino said.

“I would avoid Thursday certainly, I would avoid Friday and I might even avoid Saturday.”

Wet and warm outlook for next few months

It comes as Earth Sciences New Zealand’s (formerly Niwa) Seasonal Climate Outlook report predicts a wet and warm start for the second half of the year across New Zealand.

For Bay of Plenty, Northland, Auckland and Waikato, temperatures were very likely to be above average (60% chance) and rainfall totals above normal (45% chance) from July to September.

Brandolino said tropical weather patterns were expected to influence New Zealand over the quarter leading to “potentially significant rainfall and increased risk for flooding, particularly in already-saturated areas”.

Rainfall is expected to be above normal in the north of both islands, and near normal or above normal elsewhere. Photo / Earth Sciences New Zealand

“Rainfall is expected to be above normal in the north of both islands, and near normal or above normal elsewhere, except for the West Coast of the South Island, where drier than usual conditions are possible.

“Seasonal air temperatures are expected to be above average across all regions of New Zealand for the three-month period,” Brandolino said.

While cold snaps and frost would occur, they were expected to be less frequent than usual.