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ClimateWatch: How October is shaping up (and the rest of 2021) (+14 Maps & Video)

We’re in the thick of spring now so expect more turbulent weather, but despite all the chaos in our weather pattern we are seeing some order come back in this month – and that could encourage milder weather for many and a slightly drier pattern than we had in September.

Week One kicks off with chaos – with highs and lows all over the place. In fact a high pressure zone will extend well south of NZ to almost reach Antarctica – ensuring the Antarctic ice shelf in the NZ/Australia area will have a surge of warmer than usual weather in the first week of October. NZ will also be warmer than average with sub-tropical winds and northerlies in the mix, followed by westerlies. A low should also bring some rain into the West Coast and North Island (even dry eastern regions).

Week 2 is when you start to see a bit more order in the weather pattern. Around October 7th high pressure should be departing the NZ area bringing back another surge of warm nor’westers and some wet weather briefly from the west – and maybe the upper North Island too, on the back end of that departing high.

Week 3 looks similar to the start of Week 2, with more high pressure around the Tasman Sea, more nor’westers into the South Island and perhaps some departing wet weather from the North Island.

The month of October is likely to see more days with milder than average winds for NZ and rainfall should be about normal to drier than normal for many.


Departure from Normal – Rainfall – First week of October
Red = Drier than usual, White = Normal rainfall for this time of year, Blue = Wetter than normal
Total Forecast Rainfall through to the end of October 15 (GFS)
Total Forecast Rainfall through to the end of October 15 (GFS)
Close Up of NZ
IBM’s monthly outlook shows most of NZ leaning slightly drier than normal, although parts of Northland, the Far North, Southland and Coastal Otago may be about normal.
For the rest of 2021 it looks as though the entire South Island leans a little drier than usual, and a large portion of the North Island. Normal or above normal rainfall may impact the Far North (overdue there!), parts of Northland, Bay of Plenty, East Cape and Hawke’s Bay. You might say this long range map even looks a little bit like there’s a hint of La Nina in the air (which there is – but isn’t locked in).
Most regions have soil temps into double digits/mid teens now.
IBM’s global temperature forecast for October shows NZ leaning, once again, about 0.5C above average.
IBM global temperature for the rest of 2021 suggest NZ leans 0.5C to 1.0C above normal over the coming 3 months. There may be some localised exceptions, but the overall theme is leaning warmer. Note much of NSW leans cooler with green shading.
SST (Sea Surface Temperatures) for the last day of September (courtesy of NOAA) shows warmer than average sea conditions around Fiji and Vanuatu, but not around Queensland. NZ, for the most part, leans warmer than average – which encourages a higher chance of cloud and rain.

Side Note: Notice the blue blob up near Japan? That’s Typhoon Mindulle stirring up cold water and bringing it to the surface. As of Sept 30 Typhoon Mindulle was generating waves of almost 16 metres (48 feet)!
Australian Government (BoM) says a La Nina Watch is now in place – this is not to say it’s here, but that it’s possible. It’s worth noting that La Nina has been possible for much of this year.


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