Gisborne and the East Coast could be hit by up to two months worth of rain in just a couple of days as the remains of Cyclone Fili cross over the region.
Heavy rain is expected to hit the region around 10pm on Tuesday.
1News weather presenter Dan Corbett said as the storm deepened, the energy will increase and bring tropical moisture that will see the East Coast hit with a huge amount of heavy rain.
"Gisborne will be hit with 20, 30 or 40mm of rain per hour and it [the storm] literally just sits there," Corbett said.
The "sting in the tail" of strong gale force winds would follow on Wednesday night and into Thursday morning.
"By the time we're done, that could easily be a month’s or two months worth of rain," Corbett said.
Meanwhile, 1News reporter Kristin Hall said East Coast residents were "on edge" as they prepared for more potential flooding, just weeks after heavy rain decimated the area.
Of concern is the Mangahauini Bridge in Tokomaru Bay, which has only just been repaired after part of it was washed away during the flooding last month.
MetService said people on the East Coast can expect dangerous river conditions and significant flooding.
"Slips and floodwaters are likely to disrupt travel, some roads may become impassable possibly isolating communities, and power outages are also likely," the weather service said.
"In addition to significant rainfall, severe gale south to southwesterly winds are also forecast, which could damage trees, powerlines and unsecured structures."
MetService urged people in the region to avoid being outdoors and unnecessary travel.