Cyclone Hola is set to slam into New Zealand during rush-hour, turning commutes to chaos.
NIWA weather forecaster Chris Brandolino told The AM Show the heavy rain and strong winds could be "challenging".
"I expect Sunday for the upper North Island it will become cloudy. If you're in Northland right now you'll see the breeze increasing from the east on Sunday afternoon," he says.
"By Monday morning as we're all going back to school we'll notice potentially the wind increasing, and Monday night could be a real challenging night.
"So I'm watching the Monday evening rush-hour and the Tuesday morning rush-hour for potential impacts."
MetService says if Cyclone Hola tracks southeast to the east of New Zealand, the strongest winds and heaviest rain are likely to be offshore to the northeast of the storm.
Mr Brandolino says the damage it will do will depend on Hola's tracking path.
"It's a Category 4 right now, might become a Category 5," he says.
"If it goes to the west of New Zealand, say over the Tasman Sea, as it approaches Northland and Auckland region, it will be more of a wind event and then go to a rain event.
"But if it stays to our east then we could see perhaps less wind and more rain."