A warm but very wet start to holidays

File photo / Mark Mitchell

It's going to be a wet and miserable start to the school holidays, with heavy rain, gales and possible flooding expected for parts of the North Island.

Weather Watch analyst Philip Duncan said a slow-moving low weather system and its associated front from the north of the Tasman Sea would bring patchy but heavy rain and southeasterly gusts for parts of Auckland today.

The Coromandel and Bay of Plenty ranges are also likely to get rain today with up to 90mm expected by this afternoon.

Mr Duncan said temperatures in Auckland would remain relatively mild today at 14C and 13C for tomorrow, but the weather front had the potential to become a "significant event" for the East Coast and Hawkes Bay.

MetService is forecasting up to 250mm of rain in areas north of Gisborne and 130mm in low-lying areas until the front passes on Wednesday.

But Mr Duncan predicted far worse with the possibility of 500mm of rain in the East Coast ranges.

"The low that is bringing the heavy rain is going to stall. They are in for three or possibly four days of heavy rain," he said. "We haven't seen something like this for a while. It has similar hallmarks to the one that brought heavy flooding to Whakatane and North Otago about a month ago."

Mr Duncan said conditions had been slightly warmer over the past month thanks mainly to low weather systems emanating from north of the North Island and high air pressure over the South Island that had helped to blanket the North Island from the cold southerlies.

"The six weeks after the shortest day are normally the coldest but north of Taupo we are looking at staying mild at least until the middle of July," he said. "The North Island may very well not have a winter this year. The overnight lows are nowhere near where they should be ... many places are in late single digits where they should be closer to zero."

MetService duty forecaster Heath Gullery said skiers might be a little disappointed if they were heading to Whakapapa or Turoa this week.

"The weather is warmer so there will be no significant snow for those areas," he said.

"There have been quite a number of lows from the Tasman Sea over the past month and they tend to keep things warmer than normal."