"Essentially, that's a month's worth of rain in just 24 hours - including some very heavy hourly rainfall rates - so we're urging people to make sure they take the usual precautions and stay off the roads unless absolutely necessary."
He says rivers could rise quickly, with a predicted 2.5m high tide due just before 6am tomorrow likely to put even more stress on rain-swollen rivers.
"The rain is also expected to be accompanied by gale force winds from the south-east, which again could be an issue for those in exposed parts of the region."
Mr MacDonald says Civil Defence officials will monitor the situation overnight and the usual warnings apply for farmers with stock in low-lying areas to move them to higher ground and boaties to make sure vessels are secure.
He says the warning to stay off the roads is particularly important as in previous storms some Northland motorists have put themselves and others at risk by driving through floodwaters unnecessarily.
"Floodwaters can wash out roads or carry logs and other debris which can cause serious risks to drivers and the force of the floodwaters can also wash vehicles from roads altogether.
"We're also advising people to keep an eye out for the latest weather forecasts."
