Thanks to hot air masses from Australia, forecasters are predicting a shift to warmer, drier weather this November, setting the stage for the long-anticipated El Niño summer.
The large climate pattern is set to intensify over the next three months and longer through to autumn next year. It will be a major weather contrast for parts of the North Island that last experienced an incredibly wet summer because of the La Niña.
What to expect
Weather will be a bit unsettled to start November, then move into a drying trend especially in northern and eastern parts of the country. Once we hit the second half of November we will be on the upswing, per Niwa and their meteorologist Ben Noll.
Niwa predicts below-normal rainfall for the north and east of the North Island, above-normal rainfall for the west of the South Island, and an equal likelihood for near or below-normal rainfall everywhere else.
Temperatures will likely be above average in the east of the country. The same is expected for the north of the north island. Other regions can expect near or above average heat.
Ben Noll says we could be looking at temperatures around 35 degrees Celsius, and strings of days in the 30s in the not-too-distant future.
He says, “It looks like we’re going to get some pretty hot and dry for a lot of regions, starting around the middle of the month, and that’s going to set the stage for what we’re predicting in our three-month outlook.”
The science of summer
This set-up of weather patterns reflects the classic hallmarks of El Niño in New Zealand, as does the potential for stronger-than-normal westerly winds over most of the country throughout the warm season.
“As we know, Australia has been warming up, drying out, and there’s bushfires developing – so any airmass that tracks our way from there is bound to result in some pretty hot temperatures for northern and eastern areas, in particular,” Ben Noll said.
“On the flip side, the West Coast and Southland have been enjoying some fairly decent weather recently – but once that west-to-northwest flow resumes, they’ll be getting into that real active pattern again.”
Although El Niño has helped place a buffering ridge of high pressure above the country, it’s still possible for systems to make their way around it at times – as just happened with a northern drenching from Cyclone Lola’s remnants.
El Niño is the end of a natural cycle known as the El Niño Southern Oscillation. During this cycle, changes in atmospheric and oceanic circulation warm the central and eastern tropical Pacific. Warming of the ocean affects climate across the Pacific.
El Niño occurs every 3 to 7 years on average. It usually peaks during the late Southern Hemisphere spring or early summer and then weakens the following year.
“What forms up in the tropics, if it comes down to New Zealand, that’s totally dependent on the pressure pattern unfolding near us in the mid-latitudes at that time,” Ben says.
As such, Kiwis can expect hotter and more unpredictable weather this summer. Expect the unexpected.
Impacts for industry
El Niño means Kiwis all around the country will be in for a different kind of summer this year – particularly farmers and growers.
Of note, seasonal predictions for those in the Gisborne and Hawkes’ Bay regions signal some very high temperatures through this summer, and to a lesser extent, Nelson/Marlborough, Canterbury and Eastern Otago are forecast to also see an extended run of heat over the next six months.
However, Kiwis in areas such as Southland, Otago, and Westland may be in for a bit of a “bummer summer,” with some cooler temperatures and higher-than-average rainfall over late spring through summer, due to the lower pressure systems that will sit at the bottom of the country.
MetService forecasters echoed concerns of summer drought in the Gisborne and Hawke’s Bay regions, as well as in Marlborough and Canterbury, as the mix of wind and heat will likely result in dry soils.
https://www.nzherald.co.nz/the-country/news/weather-el-nino-farmers-and-growers-advised-to-prepare/34TCSOG73NDWND2WYVNWRQI64E/ has more information for farmers and growers.