Much of the North Island entered winter well behind on year-to-date rainfall figures, and the past three months have done little to change this.
NIWA data shows south of Waikato, most parts of New Zealand through August have recorded only between 15-50% of their usual August rainfall.
While welcomed by farmers for the good calving and lambing conditions that go with a dry August, those conditions came after a particularly dry summer-autumn period.
Most regions are coming out of winter still two-thirds behind their year-to-date averages.
These areas include Hawke’s Bay, Waikato and Central North Island.
Northland was also deep in moisture deficit prior to winter, before catastrophic floods reversed that.
Tauranga and Hamilton recorded their driest ever January-April periods, with Waikato-Bay of Plenty still only having received 65% of usual rainfall to date.
WeatherWatch director and meteorologist Phil Duncan said the risk of spring turning dry quickly may be alleviated by prospects of a La Nina weather event developing.
Typically, La Nina will deliver warm, wet subtropical moisture flows and nor’easterlies across NZ.
“When we look at the indicator put out by the Australian Bureau of Meteorology, we see it has moved to alert status for La Nina,” he said.
On a scale of one to seven, one being the most extreme, it is now sitting at two, only one level off a full La Nina status.
The bureau categorises the chances of La Nina forming as having increased to 70%, three times the normal likelihood.
NIWA’s La Nina index is also placing a high likelihood on the event affecting NZ.
However, Duncan cautioned the impact of La Nina in bringing welcome spring-summer rain would depend a lot upon its intensity.
“It may be quite good news for those regions where rainfall has been low, better than having an El Nino,” he said.
He suspected the impact may be delayed as NZ moves into its typical squally spring westerly weather patterns.
“By October though, we should know how great La Nina’s intensity will be,” he said.
Any promise of additional rainfall will be welcomed by farmers as feed supplement levels are drawn down through winter.
This has been exacerbated by demand and donations made to hard hit areas, including Hawke’s Bay and Northland.
Regional council rainfall data collected by AgriHQ analyst Mel Croad highlights how dry central Hawke’s Bay still is for the time of year.
Rainfall collection data for her own property near Waipawa is 278mm for the year-to-date compared to 442mm for last year, and 620mm for the same period in 2018. The average year-to-date rainfall figure for late August in Napier is 550mm.
“I have to say, the shortfall even caught me by surprise,” she said.
Fellow AgriHQ analyst Suz Bremner, who farms west of Napier, said year-to-date they had 606mm, against a farm average of 960mm year-to-date.
Almost half that had fallen in two rainfall events over June.
She suspected supplement feed supplies will become a big issue, especially if water tables are low and crops cannot be irrigated as they usually would.
“By the time everyone replenishes their silage and balage, I doubt there is going to be much surplus around,” she said.
“It is a scary scenario, compounded by how wide-spread the dry and lack of supplementary feed issues are.”
Baker Agfarm advisor Gary Massicks said older farmers were conscious of what a dream run winter had been, and also cautious about implications from spring onwards.
“One long-time farmer said we really need 35mm a week from here on in just to get back to average rainfall levels. That is a lot of rain, but that is about right,” he said.
He suspected with lower lambing percentages this year, more crops may be going in the ground or grass committed to silage, and was confident there would be a need for it.
Duncan said La Nina could deliver some ideal growing conditions, with regular moisture accompanied by warm high-pressure systems.
“But we have to remember we are dominated by the Roaring 40s, and that is a very powerful force to alter,” he said.
The last significant La Nina event was over the 2017-18 summer when water temperatures resulted in a marine heatwave in the eastern Pacific.
This was also accompanied by three powerful cyclones that brushed across NZ – Fehi, Gita and Hola.
