The Manawatu-Wanganui regional council is warning farmers to move stock and drop fences as it prepares to open floodgates on the Manawatu River.
The Moutoa floodgates will be opened at 7.30am on Friday, with the river expected to peak at 6.4 metres by 10am.
The council says State Highway 56 is likely to be closed by flooding from 10pm on Thursday.
Rising waters in the Pohangina River will restrict access across Raumai Bridge on Valley Road from 7.30pm on Thursday.
The council said it would provide updates if the situation changes.