18 Dec 2017

December weather: who gets the rain

10:01 am on 18 December 2017

The summer heatwave is about to change, giving way to a smattering of rain and thunderstorms - and there's more to come before Christmas.

Rain generic, umbrella, raining

Photo: 123RF

After the past three weeks of hot, mainly settled weather, rain is on the way.

A front is moving from South Island onto the centre of the North Island today, bringing rain and a chance of thunderstorms.

Buller, northwest Nelson and central North Island areas from Taumarunui to Manawatu could get thunderstorms and heavy rain, MetService says. There's a lower chance of thunderstorms from Raglan to Paraparaumu and western Hawkes Bay.

Brief downpours could fall on the ranges of eastern Bay of Plenty and Gisborne.

Niwa forecaster Chris Brandolino said today's "much-needed" rain in the North Island "won't be a heck of a lot" but central and southern Waikato, Taranaki, Manawatu-Whanganui, Gisborne and Hawke's Bay regions will get around 5-15mm.

There'll be a repeating pattern of fronts bringing rain for the next week or so, MetService is forecasting.

Warm, rainy second half of summer

Though the "huge" high pressure system that brought hot settled hot weather since late November is about to change, summer will still be warmer than average, Mr Brandolino said.

"This overall warm theme will persist for the summer season."

But the rainfall pattern will change in the second half of summer and the upper North Island is in for heavy rain.

"For the summer season as a whole, rainfall will be above normal for the northern part of the North Island, so Bay of Plenty up to the Auckland, Coromandel, Northland regions.

"Which may seem hard to believe considering what's happened of late.

"But we're thinking in the second half of summer we'll see some better chances of rainfall."

The western South Island would have below normal rainfall, and the east would have near or below normal levels. The rest of the would have near normal rainfall.

MetService is predicating eastern regions are more likely to have a dry Christmas than places in the west, especially in the South Island - but it's too early to be certain.

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