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Extreme weather driven by climate change is expected to become more intense and more frequent, pushing up insurance premiums and causing headaches for local authorities.
Jim Salinger, principal scientist at the National Institute of Water and Atmospheric Research, said the consequences of climate change could not be avoided.
"As it gets warmer, floods, landslides, droughts and storms are very likely to become more frequent and intense. A one-in-20-year event could become a one-in-five-year event."
Dr Salinger said a predicted increase in westerly winds made future heavy rainfalls in western regions and droughts in the eastern regions more likely; already this year debilitating droughts have struck Hawkes Bay and parts of the Wairarapa.
Though highly populated areas - including Auckland and Wellington - are not expected to suffer the worst of weather changes, the overall rise in temperature will still increase the likelihood of storms.
But the exact impact was unknown because there were several contributing factors, including how carbon emissions are curbed.
Dr Salinger said the atmosphere could hold 8 per cent more moisture for every 1C rise in temperature, but projections for rises vary; the increase in Northland by the 2080s is between 0.6C and 4C.
It is up to each local and regional authority to monitor and deal with climate issues and related risks.
Auckland City Council says a one-in-50-year rainfall would flood 860 homes across the city.
Developers cannot build properties within 20m of the shoreline in parts of Manukau, where the council is tendering research to find out more about climate change.
Insurance Council chief executive Chris Ryan said areas more vulnerable to weather extremes included pockets of the Far North, East Cape and the South Taranaki coast.
Property owners might find it difficult to get insurance unless they were prepared to pay higher premiums.
Climate-related hazards cost insurers $800 million last year, and this year's bill looks equally ominous, including $7-10 million for the tornadoes in Taranaki, $5 million for the cold snap in the Deep South and at least $10 million each for Northland, Auckland and the Coromandel Peninsula for this week's extreme weather.
Far North Mayor Yvonne Sharp has called for more powers for local government to stop developments that put people and their homes in danger.
At present, councils can prevent such developments, but the Environment Court can overturn their decisions.
Agencies keep in touch as regions recover
Northland
Nearly 70 homes were still uninhabitable when a three-day state of emergency was lifted yesterday. This number is likely to increase as road access improves to isolated communities.
Welfare agencies are also door- knocking in Kaitaia and Kaeo, which have most of the houses deemed uninhabitable.
Big rubbish skips are available to dump spoiled food. Power restored to all but two properties in the Far North district, but 1200 still without power in Whangarei district. A $25,000 donation from Contact Energy kicked off a mayoral relief fund. Donations through Westpac Bank branches, or by calling 0800-255-556.
Auckland
Auckland Regional Council closed three regional parks - Long Bay, Shakespear and Tawharanui - until further notice due to water and power shortages. Wenderholm, Mahurangi and Scandrett regional parks were closed to camping.
Coromandel
Clean-up crews will take a week to clear fallen trees and slips. No power to 1000 homes and no reconnection expected until late tonight .
Provider Powerco - operating from the Civil Defence headquarters because its office in Thames lost its roof - said 25,000 customers had been reconnected and the remaining customers were in remote areas.
Emergency Helpline 0800-779-997
