New Zealand could be in for a sticky, humid summer as La Niña conditions arrive on our shores.
NIWA forecasts this La Niña will feel muggier than usual and above-average temperatures will be felt throughout summer across the country.
La Niña is a period where equatorial trade winds strengthen from the west coast of South America and blow across the Pacific, resulting in cooler than normal sea temperatures.
For New Zealand, it can cause high pressure to linger east of the country during summer and there are more northeasterly winds than usual, according to NIWA. Overall, summers are often more humid than average.
NIWA confirmed the arrival of La Niña conditions on Friday in its November to January climate outlook.
"Trends in the ocean-atmosphere system continued and New Zealand's weather patterns became more aligned with La Niña throughout October. According to international guidance, the probability for oceanic La Niña conditions is 96 percent this season," it said.
New Zealand last experienced a La Niña during 2011-2012.
"Northern and eastern areas of New Zealand tend to have a wetter than usual summer [during La Niña], while southern and western areas are often drier and can be prone to drought," NIWA said in a video on Twitter.
"Summer tends to be warmer and more humid than average for most. The exceptions are eastern coastal areas, which experience onshore winds and cloudy skies."
By using data from previous La Niña, NIWA said the location of the high determines the airflow pattern and therefore the weather.
It also warns the risk for a tropical cyclone is "elevated" between November and April.
"The warm seas contribute to warm temperatures on land but can also add 'fuel' to summer storms and ex-tropical cyclones."
Soil moisture levels and river flows are likely to be below normal in the north of the North Island and the east of the South Island.