Around 10 households are cleaning up after being flooded in Kawerau.
Floodwaters were up to one metre high around 4am, especially in the centre of town.
Half a dozen cars have been abandoned because of water that reached vehicle windows in some cases.
Mayor Malcolm Campbell said generally when you get rain like this, it's disappeared by now.
But he said the rain is continuing, which is making it unpleasant for some people.
Campbell said there's a lot of run-off from the hills, which has been inundating houses.
He said creeks are running extremely high so people need to be careful while walking their dogs as banks may have washed away.
Kawerau District Council staff are working as fast as they can to unblock drains.
Fire crews have pumped out a number of houses in the town.
Campbell said people need to be careful on the roads and is asking people not to drive fast through surface flooding because of the wake, which could inundate people's homes.
Campbell said the worst affected areas are Onslow Street - the main street - as well as Beattie and Valley Roads.