Clean-up crews attempting to clear roads before the Waitangi long weekend are facing an uphill battle.

Waka Kotahi warns travellers should plan ahead and expect delays, in light of the extreme damage wreaked by heavy rain in the North Island.

State Highway 23 to Raglan and State Highway 1 from the Brynderwyns to Waipu in Northland aren't expected to open over the weekend.

Meanwhile, State Highway 25 A in the Coromandel is expected to remain closed for some time.

National Emergency Response Team leader Mark Owen says there's still the likelihood of more bad weather to consider.

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