Heavy rain watch: Northern NZ in for a drenching

It's an umbrella day in Auckland, with a heavy rain watch in place for 24 hours. Photo / Michael Craig

It’s a dreary start to the week for Aucklanders, who are waking up to wet and windy conditions.

A heavy rain watch has been in place since 3am this morning and will remain until 3am on Tuesday, as a rain band moves down over the country. The watch applies from Papakura northwards and to Great Barrier Island.

Northland is also under a heavy rain watch south of the Bay of Islands until 3pm today. The Coromandel Peninsula and Hunua Range will be under a heavy rain watch from 6pm today until midday on Tuesday, although this timing could change.

Subtropical air is affecting those regions, bringing a slow-moving rain band with “embedded heavy falls”, MetService said.

“There is a risk that the rain-band could become stationary at times, increasing rainfall accumulation in localised places, where amounts may approach warning criteria, especially in the east. Thunderstorms are possible.”

Mother Nature has a bit of La Niña hangover and is bringing us a subtropical low to start the week 🌧

Expect to see some unsettled weather - particularly in the upper North Island where there is a risk for thunderstorms ⚡️ pic.twitter.com/p4iwg9r4ov

— NIWA Weather (@NiwaWeather) September 3, 2023

MetService meteorologist Alwyn Bakker said on Sunday that the three heavy rain watches were at the lowest rating, yellow.

“That means we’re expecting heavy rain for those regions, and there’s a chance of seeing warning amounts (50mm within six hours or 100mm within 24 hours), but it’s not a high enough chance on a broad scale to issue a warning.”

Rainfall may approach the warning criteria if the rain stays in one area and gives it a pelting, especially in the east.

“It’s that slowness that’s the potential issue; slowly moving systems have a longer period of time to rain over any particular area, so rainfall accumulations are usually higher than for faster-moving systems.”