A State of emergency has been declared in Whanganui District this evening.
The declaration was made by Whanganui mayor Hamish McDouall shortly after 5:30pm via Facebook.
The announcement is in response to the rising level of the Whanganui River, which has reached 10m near the township of Pipiriki.
Data from the Pipiriki recording station suggests levels will rise to heights of 17 metres by around midday tomorrow (Wednesday), breaking stopbanks and causing inevitable flooding.
Mayor McDouall says: "We have heard there could be a significant flood event tomorrow."
Whanganui will be particularly vulnerable between the hours of 7pm and 11pm tonight, he adds.
Evacuations are likely, with Mayor McDouall saying: "People on Anzac parade, Tauo Quay and Pipiriki should be evacuated from their homes."