A heavy rain warning has been issued for the Bay Of Plenty, by Bay of Plenty Civil Defence.
Rain is forecast to become heavy around noon tomorrow.
In the 12 hours from noon until midnight Wednesday, 70-90mm of rain was expected to accumulate with peak intensities of 15 to 25mm in thundery rain.
Localised flooding and slips are possible.
Metservice said a deepening low was expected to move southeastwards across the North Island, bringing a burst of heavy rain during Wednesday.
Watches have been issued for many places, but for the Bay of Plenty and Rotorua a severe weather warning is now in force.