The Wellington region may be in for a second dumping of heavy rain in less than a month and authorities are asking locals in flood-prone areas to check and clear drains.
Wellington City Council's acting chief infrastructure officer Mike Mendonça said the rain was expected to hit from about midday on Sunday.
Residents should check street drains and clear them of leaves or rubbish in the next day or so, he said.
"We had some serious flooding when the region was last hit by torrential rain on Saturday 17 July – and residents can do their bit to reduce the problems if they just take a broom to their nearby street drains to get rid of any built-up leaves or rubbish. Every little bit helps."
That weekend the region experienced one-in-10-year rainfall. Motorways were shut, businesses were flooded, trees came down, and a wastewater pipe burst under State Highway 1.
Mendonça said the council and Wellington Water crews were currently on high alert and checking the region's infrastructure ahead of this weekend's forecast rain.
This work includes checking all culverts and outlets are clear, checking all wastewater and stormwater pumps are working properly, and the deployment of transportable pumps into known high-risk areas.
Sunday's heavy rain was expected to be accompanied by southerly gales, which could bring down trees and slips, Mendonça said.
"The ground around the region is already wet from the rain over the past few weeks so that usually means trees are more likely to topple in high winds and slips will come down."
Authorities have advised motorists to take extra care on the roads on Sunday and Monday.
"You never know if there'll be a tree or slip down round the corner on some of our twisty roads – so the advice is to keep speeds down and drive to the conditions", Mendonça said.