Forecasters are warning the areas north and south of Gisborne could get hammered by thunderstorms and heavy rain on Friday.
A severe weather warning has been issued for the Wairoa District and Gisborne south of Tokomaru Bay, with MetService saying the rain could cause streams and rivers to rise rapidly and possibly flooding and slips.
Up to 90mm of rain may fall during the period and peak intensities could reach 20 to 30mm per hour.
However, it should clear by Friday afternoon.
"The low is forecast to move away to the east this afternoon and the rain should ease," MetService said.
Meanwhile, the heavy rain warning for Wairarapa, Taruarua and Hawke's Bay south of Hastings has been lifted.
The Whanganui River levels have slowly dropped overnight and are predicted to continue to do so on Friday, Civil Defence says.
The river's flood barriers were activated on Thursday as a precautionary measure but Horizons Regional Council corporate and governance group manager Craig Grant says there is no concern for a breach.
"With the peak occurring overnight, we felt the barriers provided some assurance. We will continue to monitor the situation," he said.
The Manawatu River is also closely watched, with the river peaking at 4.3m at 2am on Friday.
Horizons staff are on standby in case the Motua floodgates need opening later in the day.
Evacuations have begun to remove 120 trapped overnight at Ruapehu's Blue Duck Station lodge by slips and floods, Civil Defence says.