"Heavy rain may cause streams and rivers to rise rapidly and there is a chance we may need to close some roads due to flooding and slips.
"If you need to head home after the long weekend tomorrow, please stay alert, increase your following distances and keep your speed down.
"Watch out for unexpected hazards like surface flooding in low-lying areas, potholes, slips or fallen trees. Heavy rain can also reduce visibility", Hankin said.
Before travelling motorists should check the Waka Kotahi travel information site journeys.nzta.govt.nz for latest updates on road closures.
MetService Meteorologist Dan Corrigan said 120 to 180mm of rain was expected to fall on the ranges, and 70 to 110mm on the coast.
"It is probably the first really significant rain event of the year. It has been an incredibly dry 2022."
He said the heavy rain would likely cause streams and rivers to rise, slips and possible surface flooding.
"It's falling on to already really dry soil, and that heavy rainfall up in the ranges is going to go into the rivers and flow out through the coast."
He said the most significant rain is expected on Sunday and Monday, and the rain is expected to ease off for Tuesday.
"Just a cloudy day with a pitter patter of rain so to speak, compared to the more persistent rain Hawke's Bay is seeing today and tomorrow, and Thursday is looking like a sunny day."
He said temperatures across the region would continue to be cooler, sitting in the low 20s rather than high 20s.
"Notably cooler temperatures during the day than the past week, when we have been sitting under a humid subtropical air mass, with that rain band pushing up and bringing some southeasterly winds."
He said the weather was associated with a heavy rain system affecting the west coast earlier in the week.
"While we are expecting some heavy rain with this, we are not expecting the extreme quantities of rain that we saw on the west coast or on Mount Taranaki."
