The BNZ building in New Plymouth has been evacuated after heavy rain damaged the roof.
The second floor roof caved in at 2.30pm and the bank was closed.
Rain has also caused sewage overflows and localised surface flooding in New Plymouth.
Sewage overflows have been reported at three sites and warning signs have been erected.
Brougham Street in the city has been closed due to sewage.
The forecast is for more heavy rain and drivers are warned to watch out for possible surface flooding.
The council has so far received more than 110 calls from the public about flooding or damage.