NZ‘s climate outlook for August

Tracking August's air pressure - the highs and lows. Images: WeatherWatch.co.nz

The month of August is kicking off with some big high pressure systems, says WeatherWatch.co.nz 

"We do have a couple of areas of low pressure from the Tasman Sea that should produce areas of rain in the north and west of both islands."

Eastern areas tend to lean drier, especially the North Island's east coast.

"By mid-month we may be getting into more of a westerly flow - which for some regions may feel like early spring.

"But a cold change in the second week of August may be a wintry one with snow on the southern ranges and a nationwide southerly change likely dropping temperatures.

More evidence that the big highs to the west and east will squeeze the life out of the Tasman Sea low this weekend. Some regions in NZ will get rain and showers (especially the West Coast and the Far North and parts of the upper North Island).

"Temperatures, generally speaking, look to lean warmer than average with a lot of sub-tropical, northerly quarter and westerly quarter airflows coming up.

"Northland and the Far North may also lean drier than normal with Auckland in the boundary for normal rainfall, possibly even a little wetter than normal - here's hoping this comes true for the Hunua Ranges and the water storage dams."

SEPTEMBER AND OCTOBER:

Long range data from IBM suggests a similar pattern continues on. That western and southern parts of NZ look to lean wetter than average (only slightly) and eastern and very northern areas lean drier.

Temperatures for the next three months look to lean warmer than average by a degree or so in most regions.

"This is an overall estimate - of course there will still be wintry cold snaps in the mix, but the warmer than average weather for the end of July looks set to continue into August," says WeatherWatch.co.nz.

A lot of high pressure about but another low in the Tasman Sea - and this one may deepen quite quickly over the NZ area. It may also dredge up a cold, wintry, southerly for the second week of August.

ACCURACY:

"Long range forecasting is a bit of an art. A lot of science goes in to it but New Zealanders need to factor in other things - like the fact we're mainly two mountainous islands partially in the windy Roaring Forties belt of weather.

"That our mountains and ranges can dramatically alter rainbands and temperatures. And that one single low or high can reverse an entire monthly outlook due to our nation's small size and the bigger power of the weather systems.

"Still, IBM says there is a 65% accuracy rate with their extra long range data - which is trustworthy enough to be factored into your thinking. Long range forecasting is to help you see regional developing trends - it's not really a forecast for your specific property, so factor in the neighbouring areas/regions too as the more you understand the big picture the more it will make sense locally.

"As always, we value your feedback if you think we were way off the mark last month. Some microclimates buck trends, but hopefully this big picture outlook is of some help to those of you planning ahead."

An air pressure sandwich! High pressure in the top half, low pressure in the bottom half and westerlies winds are the filling in the middle. Some might say this looks like a spring weather pattern forming.

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