Waikato Regional Council flood management staff are on alert following a heavy rain warning for parts of the region over the next 30 hours from 2pm on Wednesday.
MetService has warned that up to 120 millimetres of rain could fall in the areas from Raglan to Lake Taupo and from Hawera to Mt Ruapehu.
Other parts of the region could expect up to 50mm.
The council says river levels have been high after rain last week, although they have started to recede.
Land is still saturated, increasing the risk of surface flooding, and the council will be closely monitoring levels.
