El Niño expected to impact Murihiku Southland bringing more rain
While October delivered a reprieve from saturated early spring conditions, wet and windy El Niño conditions are likely to persist in Murihiku Southland during November and into summer, forecasters warn.
Since Environment Southland's rainfall records began in 1970, five of the seven wettest Septembers on record have occurred since 2020 – making it challenging times for pasture management.
A very strong El Niño is expected to remain an important influence on Murihiku Southland’s weather throughout summer.
MetService’s latest four-week weather outlook suggests a variable November, with wetter than normal conditions possible early in the month, followed by a drier period before rainfall returns later in the month.
Looking across the longer November to January period, Earth Sciences New Zealand (ESNZ) expects enhanced westerly winds and an increased likelihood of above normal rainfall for Southland, south Westland and Fiordland.
Environment Southland Principal Scientist Hydrology Chris Jenkins said forecasters expect the event to reach its peak during early summer; with signs it could rank among the strongest El Niño patterns ever recorded.
“We're likely to see more wet and windy periods in Southland through spring and into summer. Although average river levels are expected to remain near normal over the three-month outlook, periods of heavy rainfall could still increase the risk of flooding.”
Temperatures are also expected to be more variable than usual, with pronounced swings between warm and cold conditions.
“Flooding and wetter conditions can have significant impacts on agriculture and cause increased erosion and runoff into waterways,” he said.
These conditions could create ongoing challenges for farmers as they move through spring cultivation and paddock management.
Environment Southland Land Sustainability Manager Simon Stokes said cultivation was well underway following the extremely wet September. Still, soil moisture levels remained high in many parts of the region.
“Cultivation will have been on wet soils in some areas, and some farmers are going to need to break down soils further to get them prepared properly as a seed bed.”
Recent sunny weather may have caused the surface of some highly productive soils to become hard and compacted. This can make it harder for water to soak into the ground and for plant roots to grow. In some cases, aeration may help loosen the surface soil, he said.
Farmers preparing paddocks should also be mindful of the risk of wind erosion during the current El Niño conditions. With stronger winds forecast, fine, cultivated soil can be blown away, resulting in the loss of valuable topsoil.
“There’s a fair amount of variability to farmers’ situations across the region currently, so one size doesn’t fit all.”
In terms of effluent management, farmers were doing a great job getting pond levels down to provide a buffer for the next couple of months. The ‘little and often’ approach is encouraged with irrigation to avoid runoff and ponding on paddocks, he said.
Environment Southland is part of the Rural Co-ordination Group, which is meeting regularly to assess conditions across the region and coordinate support for affected farming communities.
The group also includes Rural Support Trust Southland and Otago, the Ministry for Primary Industries, Emergency Management Southland, Federated Farmers, Thriving Southland, Beef + Lamb New Zealand and DairyNZ.
Environment Southland’s land sustainability and compliance teams are available for free on-farm advice and support – they can be contacted on 0800 76 88 45.
