Waiheke Local Board Chair Cath Handley said the community would need to pull together to get ready and respond if there was more water than the island's drainage could cope with.
"Since the last major storm in 2017 many fixes have been put in place by owners, Healthy Waters and Auckland Transport, while other locations are still working on solutions.
"Our land is so dry it's not going to mop this water up if it's a deluge, so we all need to be on alert and to look out for less-able neighbours. It's an anxious time for those who have been flooded before," Handley said.
Weekend Forecast
The forecast on Saturday showed the low over the upper North Island should move rapidly to the east - with rain expected in many places, especially in the north.
There was low confidence that rainfall would meet warning criteria from Coromandel Peninsula to East Cape.
On Sunday, an active trough should move northwards across central and northern New Zealand, bringing strong cold southerlies and showers.
There was low confidence of heavy rain on the east coast of both islands from North Canterbury to Gisborne.
"Also on Sunday, there is low confidence of severe southeast gales in Buller and northwest Nelson, and of southerly gales becoming severe from the Kaikoura Coast to Taranaki and northeastwards to East Cape."
Your Weather for Friday
Whangārei: Rain, heavy at times, easing overnight. Northeasterlies strengthening.
High 23C Low 19C
Auckland: Cloudy, isolated showers. Rain setting in from late morning, possibly heavy from afternoon. Northeasterlies strengthening.
High 24C Low 19C
Tauranga: Cloudy. A few showers, turning to rain afternoon or evening. Northeasterlies strengthening.
High 25C Low 19C
Whanganui: Cloudy, chance shower. Northwest breezes.
High 25C Low 15C
Napier: Cloud thickening, possible evening shower. Northerlies.
High 30C 19C
Wellington: Cloudy with a few showers. Northerlies, strong for a time.
High 22C Low 15C
Christchurch: Fine at first then cloud increasing from afternoon. Northwesterlies change southerly in the afternoon.
High 28C Low 9C
Dunedin: Early rain, then fine apart from chance afternoon shower. Southwesterlies.
High 22C Low 10C