A recent NIWA (National Institute of Water and Atmospheric Research) report stated there is around a 100% chance of El Niño continuing during October through to December and a more than 95% chance it will persist through summer.

ORC’s Manager Science Tom Dyer says that Otago’s current river flows and soil moisture content are normal or slightly higher than normal for this time of year.

“The 35-day forecast is for slightly drier conditions than normal, although we do not expect significant drought related issues across much of the region over that timeframe,” he says.

However, Mr Dyer says farmers should give some consideration around preparing for an El Niño summer and ORC will continue to monitor weather conditions and provide updates.

Act early rather than later

ORC’s Acting Manager Regulatory Joanna Gilroy says farmers need to consider making a plan with contingencies, and “act on it earlier rather than later.”

“Having a plan now, will help to support making decisions later on.”

“Plenty of thought should be given to water needs over summer, how water will be managed and what feed requirements there might be,” she says.

Farmers should now check their irrigation and stock drinking water systems for any faults, undertake any deferred maintenance and consider ordering spare parts.

Ms Gilroy says ORC can assist farmers with management of water takes, especially if water takes become restricted in coming months.

Contact ORC on 0800 474 082 or a Catchment Advisor at catchments@orc.govt.nz.

Mr Dyer says river and rainfall predictions may be close to or above average for Otago, but long periods of wind can dry out soils in a short time.

While El Niño is locked in, river and rainfall are expected to be average to below average for east Otago and average to above average for inland Otago.

On NIWA’s drought index, there are no forecast hotspots over the next 35 days in Otago, however, the rainfall predictions show the north-eastern areas of the region could start to dry out.

The NIWA report says seasonal wind strength is forecast to be above normal across most of the country because of a stronger than normal pressure gradient (the difference in pressure over distance) near New Zealand; meaning there will periods of potentially damaging winds.

West Coast, Southern Alps and foothills, inland Otago, Southland – NIWA report

• Temperatures are about equally likely to be near average (45% chance) or above average (40% chance). Dramatic temperature swings from well above average to well below average are likely, particularly in October.
• Rainfall totals are most likely to be above normal (50% chance). Strong westerly fronts will occasionally impact the region, delivering heavy rainfall and a risk for flooding.
• Seasonal wind speeds are expected to be much stronger than normal.
• Soil moisture levels are most likely to be near normal (45% chance) while river flows are about equally likely to be near normal (45% chance) or above normal (40% chance).
• For inland and southern Canterbury and east Otago, periodic wetter than normal conditions may occur when rain bands may “spill over” the main divide.
• Seasonal wind speeds are expected to be much stronger than normal.

Read the NIWA report (29 September)