Figuring out the La Niña and El Niño stuff

La Niña and El Niño are both weather phenomena that occur in the Pacific Ocean and can have significant impacts on weather patterns around the world.  Collectively known as El Niño-Southern Oscillation or ENSO they have an important influence on New Zealand’s climate.

We have just come out of a La Niña phase and are currently experiencing ENSO-neutral conditions, this is expected to continue through at least the first half of 2024, with equal chances of La Niña, El Niño, or neutral conditions thereafter. However, there are signs El Niño may form during winter. Therefore, the ENSO Outlook is at El Niño WATCH. This means there is approximately a 50% chance of El Niño in 2023.

  • El Niño occurs when the ocean temperatures in the central and eastern Pacific Ocean become warmer than average, leading to changes in atmospheric circulation patterns.
  • La Niña, on the other hand, occurs when the ocean temperatures in the central and eastern Pacific Ocean become cooler than average.

So, what can we expect next season?

It’s difficult to make specific predictions about the weather in any given location, especially several months in advance. However, based on historical patterns and current climate models, here are some general trends that could be expected in the North Island of New Zealand during the summer months (December to February) in the presence of La Niña or El Niño.

  • El Niño: El Niño is typically associated with drier and warmer conditions in the eastern and southern regions of the North Island, with increased chances of drought and wildfires. The west coast of the North Island may experience wetter-than-average conditions during an El Niño event.
  • La Niña: Typically, La Niña is associated with increased rainfall and cooler temperatures in the North Island of New Zealand, especially in the eastern and northern regions. This could lead to a wetter-than-average summer with a higher risk of flooding and storms.

La Niña and El Niño account for less than 25 percent of the year-to year variance in seasonal rainfall and temperature at most locations. Nevertheless, the effects can be significant. It’s important to also note that the strength and duration of these events, as well as other factors such as local geography and atmospheric conditions, can also influence the weather patterns in New Zealand. Therefore, it’s always advisable to monitor the local weather forecasts and warnings issued for the most accurate and up-to-date information.


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