Southern residents are being urged to prepare for “significant” weather impacts over the next three months, as El Nino conditions start breaking atmospheric measurement records.

Earth Sciences New Zealand forecasting principal scientist Chris Brandolino said El Nino conditions were now strengthening in the tropical Pacific atmosphere and ocean.

While the event was still in its early stages, it had already creating the strongest atmospheric measurements on record for July and it was expected to impact on New Zealand’s weather over the next three months, he said.

“There is now a 90% likelihood for El Nino to reach or exceed very strong intensity during the outlook period, with peak conditions and potential significant impacts most likely during the 2026-2027 summer.

“It is likely to develop into one of the strongest in recent history.”

Mr Brandolino said the El Nino-related influences on regional weather patterns were expected to become more apparent during spring and would include periods of active westerlies, an increased risk of unusually windy conditions and notable temperature variability.

On the West Coast, Southern Alps and foothills, inland Otago and Southland, temperatures were equally likely to be near average or above average and rainfall totals were most likely to be above normal.

“The risk of active weather events, including heavy rainfall and strong winds, is forecast to increase during spring.”

Soil moisture levels were most likely to be near normal and river flows were equally likely to be near normal or above normal, he said.

Along coastal Otago, temperatures were about equally likely to be above average or near average.

“The likelihood of increased temperature variability, including larger swings between warm and cool conditions, as well as periods of unusually windy weather, is expected to increase during spring.”

“The likelihood of below normal rainfall in several regions is likely to reduce groundwater recharge, creating challenges for water-reliant sectors.”

john.lewis@odt.co.nz