A strengthening Pacific El Niño is beginning to shape Northland's weather, and the region's August rain may prove only a temporary reprieve, according to Northland Regional Council's August climate and hydrology report, covered by Susan Botting for Local Democracy Reporting in Farmers Weekly.

The report says El Niño conditions strengthened considerably during August, showing the strongest warming trend on record, with peak conditions expected in late spring or early summer. Chief executive Jonathan Gibbard told the council's mid-September Te Ruarangi committee that this could be the strongest El Niño on record and bring conditions unlike anything Northland has experienced; the developing event is compared with the powerful 1997-98 pattern, which brought drought to parts of New Zealand and hit farming and water supplies.

El Niño typically brings more frequent westerlies and drier conditions to Northland, raising the odds of below-average rain, lower river flows and less groundwater recharge. Forecasters now put below-average rainfall as the most likely outcome for September to November, with temperatures more likely above average.

That is despite a wet August: the region recorded 172mm, 108% of the long-term monthly average, most of it in a late burst of subtropical weather across the Far North, Hokianga and the east coast from the Bay of Islands to Whangārei Heads, after a significantly drier July. Winter rainfall overall was still only 82% of the seasonal average. Touwai near Whangaroa Harbour had the most rain at 325.5mm (147% of normal), Cape Reinga 186.9mm (181%) and Marsden Point 178mm (148%), while Dargaville recorded just 60.2mm (48%), and Kaikohe, Opouteke and parts of Kaipara were also below average.

River flows in August ranged from normal to extremely low and were mostly below normal to very low across western, mid-north and southern Northland, improving only along parts of the east coast. Groundwater recovered after the late rain and most monitored sites are normal or below normal, but levels are extremely low at Taipā and Awaroa near Kaitaia and low at Poroti, Maungatapere and Maunu. Soil moisture is at or near field capacity across most of the region, a cushion for spring that the report warns may be hard to keep if spring rain is below average as expected.

Reported by Susan Botting for Local Democracy Reporting, published by Farmers Weekly.

Source: Farmers Weekly NZ