ClimateWatch: AUGUST sees big highs and big lows + 15 maps and video | Weather report

AUGUST + SPRING OUTLOOK — There is no shortage of big highs and big lows in August in New Zealand and Australia, as La Nina continues to slowly look to come back at some point.

The long-term forecast for New Zealand is warmer than average with rainfall over the two main islands – particularly northern New Zealand, where at least another 100mm is expected over the next two weeks.

Large highs continue to move from Australia, but large lows are also mixed in.

This means that the word “variety” remains in the forecast with a good mix of sunny and mild days, and windy and more humid days. Usually, the variety of our weather is good for the economy, with most farmers and growers benefiting from a healthy mix of weather – usually anyway.

Here are the maps and more details on how AUGUST, SEPTEMBER and OCTOBER are going in our part of the world.

The latest news from BoM (Bureau of Meteorology) from Australia shows that we are still in a La Nina look.
BOMs The international model average shows La Nina trying to get back in the spring…but only narrowly.
Looking at all reliable models (please note that the New Zealand government agency Niwa does NOT contribute to global open data for their own business reasons), you can see that ALL reliable international models are either in the neutral zone (white) or leaning towards blue (La Nina). No model indicates El Niño. Open data and maps courtesy of Nomenclature from Australia – with thanks.

BOMs The Sea Surface Anomaly map shows that conditions around the equator are mostly at normal temperatures now, but it is still warmer than average around the South Pacific islands and much of the neo side. -Zealanders of the Tasman Sea. Warmer sea surface conditions favor fuel lows, thunderstorms and rainmakers.
A closer view of New Zealand and many coastal areas of New Zealand remain in an official marine heat wave. It’s not La Nina related, it’s our local sea surface temperatures that show they are a few degrees above normal on the North Island in particular. Our thanks to – and for releasing the maps to share for the greater good of all Kiwis.
Current sea surface temperatures in New Zealand –


Week 1 kicks off with a lot of high pressure over Australia and northern New Zealand – even in the South Pacific islands. However, it is balanced by huge areas of low pressure (and deep depressions) south of Australia during this first week. This will create gales to strong gales around Western Australia (especially the South Coast) and coastal parts of SA, VIC and TAS. These gusty westerly winds will also reach New Zealand, becoming more wintry southerly for a while on the first weekend of August for the South Island (August 7).
Week 2 sees stronger highs with three of them near New Zealand – one to the east, one to the southwest, and the other approaching Australia. However, in the middle of these (in the central Tasman Sea) is an area which, combined with warmer sea surface conditions, could develop into a rainmaker/low pressure area at slow moving. One to watch.
Week 3 kinda sees the old switch-a-roo! Now the low covers both Australia and the New Zealand area as highs drift further south and northeast. This allows rainmakers to move slowly across New Zealand – and a low centered over central New Zealand can also lead in rain to eastern parts of the South Island – not locked that far , but shows that long-term forecasts are even more unstable.

RAINS COMING IN AUGUST…and for early spring

16-DAY RAINFALL MAP – Northern Australia leans mostly dry (yet another sign that La Nina is not currently active) while a line of rain activates west to east tracks from Western Australia to New Zealand .
CLOSE UP – 16-DAY RAINFALL MAP (Through August 16) – This close view of New Zealand shows 200mm+ for the west coast and 80-150mm for parts of the North Island. The southeast of the South Island could have the lowest totals of all for the next 16 days ahead. (GFS data). Although the rainfall is not perfectly painful as shown in this map, it does give a clear picture of rain moving towards New Zealand from the west and north over the next couple of weeks.
Long range data of IBM Watson (the most accurate forecaster in the world) shows that rainfall in New Zealand in August is quite close to normal (+/- 12mm). Sydney leans much wetter than average. The warmer and slower set-up this month means rainfall totals in some pockets may be above normal (as we saw in July in New Zealand), so landslides and flooding located in the New Zealand region can still be expected this month.
THREE MONTHS OF RAIN – Departure from Normal. Again, New Zealand is mostly in the “normal” range, but parts of the northern North Island seem to lean wetter than average, while Fiordland can lean drier. Sydney is still leaning much wetter than usual.


AUGUST – New Zealand continues to lean 0.5 to 0.8°C above average… which it has been doing for the past year or two.
AUG – SEP – OCT – No change in the New Zealand zone, still dipping around 0.5°C above normal – unlike NSW which mostly dips around 0.5°C below.

ClimateWatch is New Zealand’s only independent Climate forecaster and are proud to be associated with IBM Watson – the most accurate forecaster in the world. These updates are brought to you in association with and with thanks to the Australian Bureau of Meteorology, who support open data. – supporting farmers and producers who help feed New Zealanders. (Proud to be a company).

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