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ClimateWatch: August’s Outlook (+15 Maps & extended Video)

August is looking to lean warmer than average with rain events off and on from the west – but also some large high pressure coming out of Australia. Leaning warmer than average doesn’t mean it feels warm, nor does it mean we won’t have wintry changes – but generally speaking the nation looks to be a little milder.

Some large high pressure systems remain over Australia and northern areas while large lows and storms (normal for August) remain over the Southern Ocean.

July was warmer than average and that’s helping contribute to some fairly mild soil conditions around the country.

Soil temperature
Soil moisture anomaly
Soil moisture – Liquid water in the top 2 metres of soil

August is looking to start off on a colder note and maybe quite unsettled at times, but as we head into mid August a large high from Australia is likely to move through encouraging westerlies and limiting stormier weather in the NZ area.

August is a highly unstable month weather-wise and while we do our best to cover the general weather patterns in the weeks ahead there can aways be a surprise storm or snowy blast.

As usual, we’ve marked where the highs and lows will be at the start of the next few weeks coming up. For the most part the weather systems are moving from west to east.

Large lows remain south of Australia in the first week and this will ‘spill over’ into the New Zealand area dropping temperatures and encouraging the chances of some severe weather in NZ (severe gales, heavy western rain, some snow higher up).
Week 2 kicks off with a bit of an evening out process with large storms (normal for August) in the Southern Ocean and a powerful extra wide high pressure zone moving out of Australia. This will move into the northern NZ area encouraging fairly ‘mild’ westerly winds to blow over NZ.
Week 3 kicks off with a fading southerly and a high potentially moving in. In August the stormy Southern Ocean can make it harder being precise about the placement of air pressure systems longer range like this, but if this strong high does roll in it may bring a frosty period of weather, followed by milder northerlies.


Rainfall next 7 days (start of August) – Departure from normal.
Red = drier than normal, White = normal rainfall for this time of year. Blue = wetter than usual.
This set up shows the South Island’s West Coast looking wettest – in other words, normal weather for August. Biggest downside – still very dry in Hawke’s Bay.
Fairly normal August set up with heavy rain on the West Coast (around 150 to 300mm in the first half of the month). Eastern areas will be driest. This suggests a westerly flow will be dominating.
A closer up version of expected rainfall (GFS) next 15 days.
AUGUST rainfall – Departure from normal
Suggesting while the first week or so of August may be wet on the West Coast, the entire month may lean drier than usual – suggesting the forecast highs may well come in.
Rainfall – Departure from Normal
Longer term and rainfall looks to lean a little wetter than usual (not a lot) with some some areas normal or even drier than usual (such as the eastern side of the North Island and around Fiordland, Otago and Southland.

July was warmer than average generally speaking across New Zealand. It shows that even though it’s still cold, it’s not as cold as what has been recorded historically at this time of the year. August is looking similar to July, leaning a little warmer by half a degree to a degree – and that may be due to an uptick in westerlies.

Temperatures – Departure from Normal
NZ leans warmer by 0.5 to 1C above normal
Temperatures – Departure from Normal
Most of NZ leans 0.5 degrees above normal, maybe closer to 1C above normal
SEA SURFACE TEMPERATURES (JULY 30) – Departure from Normal (NOAA)
Shows marine conditions around NZ are warmer than usual at the moment.
TOP ROW: Shows some signs of La Nina forming in the months ahead in the Pacific Ocean
BOTTOM ROW: Shows the Indian Ocean Dipole (Basically their version of La Nina) currently in action but may ease off to Neutral in December.
Both of these rows indicate more wet weather around the tropics north of NZ and around Australia too. This doesn’t directly impact NZ day to day or even week to week – but does suggest more rainmakers will be nearby to the NZ area and some may reach us.
Details above via Australia’s Bureau of Meteorology (BoM). NZ’s Niwa has announced they are now in “La Nina Watch”.



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