KEY POINTS:
As the third storm in a week heads for the upper North Island, insurance payouts from the first two big storms could reach $50 million.
A deep, fast moving low and associated fronts are forecast to cross northern and central New Zealand this weekend, bringing strong winds and rain.
The Insurance Council says it is still early days, but the widespread nature of the storms and their ongoing impact could see costs skyrocket.
It says the consequences of climate change are now forcing increases in premiums.
Civil Defence is keeping a close eye on rivers in the Waikato region. The Waipa River system and the Waikato River are running high and are being monitored by Environment Waikato and Mighty River Power.
The heaviest rain is expected about higher areas from Taranaki across to the Central Plateau and eastern Bay of Plenty, including Taumarunui,Waitomo and the headwaters of the Whanganui River.
It means more flooding, slips and treacherous conditions on the roads.
Thousands of weekend sporting plans are also likely to be disrupted again.
Rugby games for 7000 juniors and 6000 secondary school players have been cancelled as councils try to dry soaked fields.
"This rain will be falling on already sodden ground, so further flooding and slips are likely, and rivers and streams will swell quickly," said MetService spokesman Bob McDavitt.
The bad weather will hamper the big clean-up after the last storm.
Main rail and road links remained closed in the South Island.
Taranaki, the Central Plateau and eastern Bay of Plenty are expected to get this heaviest rain in this weekend's storm. Up to 140mm of rain is forecast in higher areas.
Mr McDavitt said the storms of the last 10 days had made July much wetter than normal, particularly in the north and east of the North Island.
Some areas had received almost twice as much rain as usual. In Auckland, rain gauges showed a 60 per cent increase on an average July.
Niwa figures show areas along the east coast from Northland to Whakatane received up to two-thirds more rain than normal. The heaviest rain was in Paeroa, which had nearly three times the average - 416mm for the month.
"They've exceeded their record by 70mm," climate scientist Andrew Tait said. "That is incredible."
The bad weather has also hit weekend sport.
Auckland had rain every weekend in July, washing out hundreds of rugby, soccer and hockey games.
Last weekend, the Auckland Hockey Association cancelled games for the first time in five years.
Auckland Rugby cancelled four of the last five weekends of junior rugby, which club rugby manager Matt McHardy said had taken a toll on young players' morale.
"We hear that players are distraught when they wake up and ... Mum or Dad says, 'rugby's cancelled', and they burst into tears."
The Auckland Sunday Football Association may be unable to finish its season after scrapping matches three weekends last month because of the weather.
Registrations officer Trevor Brook said there were only two free weekends before councils closed pitchs to the association's 36 teams, and the most any team had played was 10 of 14 games.
WASHED OUT
* Another storm threatens more flooding and insurance costs are likely to hit $50 million.
* Weekend sport has taken a pounding from repeat cancellations.
* The wettest spot this month has been Paeroa with 416mm of rain - the most in July since 1914.
- with NEWSTALK ZB
