A potential “period of heavy rain” has been forecasted for mid-to-late January, particularly for the North Island and northern South Island, according to a seasonal outlook.

NIWA released its seasonal climate outlook for the period between January and March earlier today.

Meteorologists said potential rainfall in January was being influenced by the type of El Niño being experienced, which has an important influence on New Zealand’s climate.

“The type of El Niño being experienced will likely result in more variable rainfall patterns than experienced during strong El Niños in the past.”

They added: “This may contribute to a risk for heavy rainfall and flooding from the third week of [January], particularly in the North Island and northern South Island.

“Significant heat and humidity is also expected to build across the country in mid-to-late January, lasting the longest in the North Island.”

Over the three-month seasonal outlook, average rainfall is most likely to be near normal in the north and east of the North Island and west of the South Island, NIWA said. Near normal or below normal rainfall is about equally likely elsewhere.

“All outlooks are for the three months as a whole. There will inevitably be relatively wet and dry days, and hot and cold days, within a season.”

In Auckland, Northland, Waikato, and Bay of Plenty, over the three-month period, temperatures are “very likely to be above average — 60% chance”.

“Spells of hot and very humid conditions are expected in mid-to-late January.

“Rainfall totals are most likely to be near normal — 45% chance. Spells of heavy rain may occur in the second half of January. However, the season may also be defined by longer dry spells, particularly in February-March,” according to NIWA.

In the region covering Gisborne, Hawke’s Bay, and Wairarapa, “temperatures are very likely to be above average — 60% chance”.

“Spells of hot and very humid conditions are expected in mid-January. Rainfall totals are most likely to be near normal — 45% chance.

“Spells of heavy rain may occur in the second half of January. However, the season may also be defined by longer dry spells, particularly in February-March.

“According to the drought index, moderate to very dry conditions are occurring across southern parts of the region,” according to NIWA.

In Wellington, central North Island, Taranaki, Whanganui, and Manawatu, “rainfall totals are about equally likely to be near normal (40% chance) or below normal (35% chance)”.

“According to the drought index, moderate to very dry conditions are occurring across parts of the region, with longer dry spells expected to continue over the next season.

“Spells of rain, possibly heavy, may occur in the second half of January.”

Meanwhile further south in Christchurch, in the region covering coastal Canterbury and eastern Otago, “hot, humid conditions are expected around January 10, possibly giving way to cooler conditions in the second half of the month”.

“Rainfall totals are about equally likely to be near normal (40% chance) or below normal (35% chance). According to the drought index, moderate to extremely dry conditions are occurring across parts of the region, with longer dry spells expected to continue.

“Periodic wetter than normal conditions may occur when rain bands ‘spill over’ the main divide or during strong southerly changes.”

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