A large high pressure system south of New Zealand later this week will expand across the South Island on Saturday bringing light winds and even afternoon cloud build-ups with showers inland (like Central Otago). With the spring equinox on Friday we typically expect windy westerlies at this time of the year – but Saturday looks calm over the South Island with mostly dry, settled, weather.

The lower North Island on Saturday is somewhat graced by this South Island high too, but a large low in the Tasman Sea coming from Australia will be bringing in the grey clouds and wetter weather further north.

Showers and nor’easters will affect the upper half of the North Island with areas of raining moving in later. Like other lows from Australia this month it’s definitely one to keep any eye on as heavy falls may be triggered – and the slow moving nature means heavy falls may set in.

On Sunday high pressure dominates the South Island while this low, centred just north of NZ, affects the upper North Island.

Those in between the air pressure systems (the lower North Island) have an easterly flow half way between the northern low and southern high – so the weather will be a bit cloudy and breezy but should be dry.

Rain on Sunday in the upper North Island may hang around all day for some people with heavy falls here and there – the low is large but certainly isn’t very deep or aggressive and has large areas of dry or drizzle only – but it’s these unpredictable Australian rainmakers which have been causing very slow moving set-in-rains across various parts of the North Island this September, leading to some slips, floods and power cuts.

We’ll keep you posted on this low in the coming days.

– Image / 12noon Sunday rain map shows a large high over the South Island and a sizeable low north of New Zealand at the same time / Weathermap

– WeatherWatch.co.nz