Heavy rain right along the western and northern coastlines of New Zealand will set in today with the government forecaster already issuing rain warnings.

The heavy rain is thanks to a low which formed off the Sydney coastline over the past few days.  The low has moved into an area which was home to a small sub-tropical low at the weekend.

That low died away but left behind a large pool of humid air which this new low is absorbing.

WeatherWatch.co.nz head weather analyst Philip Duncan says following recent rains farmers and those in flood prone areas should keep up to date with the latest warnings, watches and weather news.

“Some parts of the country have been drenched in recent weeks while others are bone dry.  Unfortunately the bulk of this rain will be falling in areas that have already seen rain in recent weeks”,

Mr Duncan says while farmers and gardeners will be thankful for the rain he advises people to be aware of flood potential.  “This same system caused rivers to reach minor flood levels in Queensland at the weekend and we expect it will do the same here in some pockets”.

Moisture laden sub-tropical air will feed the front and may produce a few isolated thunderstorms and torrential downpours.

Motorists are advised to drive with extreme care in drizzle and heavy rain across much of the North Island and upper and western South Island.  Visibility in drizzle can be significantly reduced while heavy isolated downpours could cause unexpected surface flooding.

WeatherWatch.co.nz says the low responsible for the rain won’t be able to move because of the blocking high to the east.

“The high to our east is like a traffic light stuck on red.  The rain clouds keep building and building up behind it and are parked up over northern and western New Zealand.  The light won’t go green until sometime this weekend when the high finally moves further out into the Pacific”.

Heavy rain could linger from Wednesday to Friday in some areas but the weekend is looking more showery with less humid winds from the southerly quarter.

A few showers and spits of rain are expected in dry parts of the South Island’s south east, but not enough, at this stage, to reverse the dry conditions that are developing there from weeks of strong winds which have recently eased.

Next week will see another high cross the South Island bringing more La Nina humidity, cloud and easterlies to northern New Zealand but fairly sunny and settled weather for the bulk of South Island main centres. 

That same pattern may hold until Christmas Day. 

WeatherWatch.co.nz will issue the first Christmas Day forecast on Thursday.

– WeatherWatch.co.nz