What are El Niño and La Niña and why do they matter?

Why should you care about ENSOs, El Niño, La Niña, and Indian Ocean Dipoles?

Well, these things influence the weather worldwide. El Niño Southern Oscillation (ENSO) is pretty much responsible for what happens weather-wise. By keeping an eye on ENSO, we can figure out if we’re in for floods, droughts, or other extreme weather, and get ready for whatever Mother Nature throws at us.

First things first, what’s an ENSO cycle?

ENSO is a natural weather pattern in the tropical Pacific Ocean. It’s got three modes: neutral, El Niño, and La Niña. They all bring different weather to the eastern, northern, and central parts of the country. It usually takes about four years for ENSO to swing from El Niño to La Niña and back again.

What happens during the neutral phase of an ENSO cycle?

In the neutral phase, those trade winds blow east to west in the Pacific, warming up the western side while cooling the eastern side near South America. It’s like a giant weather seesaw. We get this about half the time, and it’s when we see what we’d call ‘normal’ weather, but floods and droughts can still pop up.

What’s La Niña?

La Niña is a weather pattern that kicks in when those trade winds get super strong. Our waters warm up even more, and South America’s waters get cooler. This setup sticks around for at least a year.

What’s the weather like during La Niña in Australia?

With the warmer water, we get more clouds, more evaporation, and more rain. That means cooler days and a higher chance of flooding.

What about El Niño?

El Niño is kind of like La Niña’s non-identical twin. During El Niño, those trade winds weaken or flip, so the warm waters head back to South America. It messes with our temperature patterns, making our side warmer, pushing the rain and clouds away.

How does El Niño affect Australia’s weather?

With El Niño comes droughts, hotter days, less rain, and fewer tropical cyclones.

Now, what’s the Indian Ocean Dipole?

The Indian Ocean Dipole (IOD) is like ENSO’s cousin, but it hangs out in the Indian Ocean. It’s all about the sea surface temps in the east and west parts of the Indian Ocean, from Indonesia to Africa.

How does a positive Indian Ocean Dipole mess with Aussie weather?

When we’re in a positive IOD, the western Indian Ocean heats up, and we see fewer clouds in our north-west and less rain in the south and Top End.

What about a negative Indian Ocean Dipole?

A negative IOD happens when the eastern Indian Ocean is warmer than the west. Winds change direction, bringing more clouds and rain, which can lead to floods in our north, south, and Top End.

When does a neutral IOD happen?

A neutral IOD is when there’s not much of a temperature difference between the east and west sides of the Indian Ocean.

Are ENSO and IOD buddies?

Yep, they’re pals. Usually, a positive IOD comes with El Niño, and a negative IOD hangs out with La Niña.

Why does all this matter?

Knowing what’s coming weather-wise is gold. If you’re aware of a flood or drought risk, you can prep your home and business. If it’s gonna be dry and you’re in bushfire territory, it’s smart to get fire-ready. If there’s a flood and storm warning, batten down the hatches.

Plan ahead, folks!

Get your hands on the BOM app and those state and territory government apps to stay in the know about weather dangers.