Rotorua residents are being advised to stay indoors after downpours flooded homes and businesses on Sunday.
Emergency services have been overrun with calls from residents left stranded by down trees and closed roads.
Rotorua Lakes Council is asking residents to stay off the roads if possible.
"There are stormwater lids popping up in some places so please stay away from any surface flooding.
"If you absolutely have to be out driving please be very careful, drive slowly through any surface flooding, be aware of the potential for stormwater lids to pop up and be aware that there may be slips and/or trees down across roads."
Civil Defence has opened an emergency operations centre at the Energy Events Centre to provide emergency accommodation to residents displaced by flooding at their homes.
A number of roads have surface flooding, with at least four large tree falls and three major slips reported.
MetService reports that 101mm of rain had fallen by midday, with another 25mm expected in the afternoon.
A severe weather warning is in place for the city until 2pm.
The storm has also battered the Coromandel Peninsula, especially Waihi and Whangamata.
Video posted to social media shows an overflowing Ohinemuri River.