People near the Esk River north of Napier are being warned to be ready to move quickly if the weather gets any worse.
Some parts of Hawke's Bay, including Eskdale, have had more than 300mm of rain and more is likely, Weatherwatch said.
Meanwhile, about 120 people will be stuck at Blue Duck Lodge at Whakahoro, on the Retaruke River in the Ruapehu District, after slips and flooding cut off the access to the lodge.
The Napier-Taupo road, closed after heavy rain caused slips and flooding, has reopened.
However, people should take extra care on the road, part of State Highway 5, and delays can be expected, with some sections down to one lane, the NZ Transport Agency says.
Most other state highways are also open.
Hawke's Bay Civil Defence says rain is expected to continue overnight and it is monitoring the situation, but the risk of flooding is easing.
It says those residents who have self-evacuated from their homes may return if safe to do so.
However, the situation could change so those in affected area should continued to be prepared to leave, if necessary.
Among those who had evacuated were campers from Eskdale Holiday Park and students from Hukarere Girls College.
There were also evacuations in Patoka, about 40km inland from Napier.
Group controller Ian Macdonald says the weather is unpredictable, and people near the Eskdale River are most at risk.
He said at the moment the rain is easing, but another heavy downpour could mean trouble.
Macdonald says the river system is short with a steep catchment so the water can rise very quickly.
Metservice says more rain is on the way for Hawke's Bay, with up to another 30mm expected to fall today.
Meteorologist Tom Adams said the rain expected to fall this evening would not necessarily be heavier, or lighter than earlier today. Localised downpours were still expected, especially about the ranges and south of Mohaka.
Tomorrow there could be rain, with heavy and possibly thundery falls, but this would be easing to occasional showers in the afternoon.
Rainfall in the headwaters of the Esk and Ngaruroro rivers, has been well over in 100mm just over 24 hours, according to Hawke's Bay Regional Council figures.
The Esk River water level at the Waipunga Bridge rose above 7m at its peak this morning, dropping back to 3.5m by 11.30am.
The heaviest was thought to be the 322mm at the Glengarry recording station from 9am yesterday to 11.15am, including 105mm in the two hours to 6am, figure similar to some of those recorded in the area at the height of Cyclone Bola 30 years ago.
Council principal scientist climate and air Kathleen Kozyniak said it appeared "quite focused", with areas north and south having not yet received anything like the same rainfall, nor that of Cyclone Bola in which some areas received over 700mm between on March 6-8, 1988.
According to on-line Metservice figures, 57mm of rain had been recorded in Hastings in the 12 hours to midday, but just 16mm in Napier, contrasting the previous 48 hours in which the 6.6mm recorded in Hastings compared with 45.8mm in Napier, mainly on Tuesday night.
At Whakahoro, 120 people will have to stay over night at the Blue Duck Lodge due to heavy rainfall.
Ruapehu Emergency Management Officer Nick Watson said slips on the access road and a flooded river had cut access to the lodge.
"Ruapehu Civil Defence has been in contact with the lodge owners and organised for a helicopter and food to be dropped in which arrived around 15:30 this afternoon," he said.
Everyone was warm, safe and happy for tonight with enough supplies for tonight and into tomorrow.
"We will be watching the weather situation overnight and making a decision on evacuations in the morning," he said.
In other parts of Ruapehu, SH43 was closed with multiple slips between Haeo and Tahora on the Forgotten World Highway.
In the Taumarunui area the water had dropped away but left several garages needing to be cleaned up.
- additional reporting, NZN