Summer time forming La Nina possibly coming to Australia

8 January 2025

Your average La Niña forms in winter, peaks in late spring, then gradually weakens through summer. However, the current edition has not played by the rule book — for only the second time in 75 years, its onset has arrived in the middle of summer.

This is something I’ve been wondering about. Over the summer months especially, I keep a close eye on the ten-day weather forecast. I’m looking out for upcoming days where temperatures are expected to exceed thirty-degrees Celsius. This because we do not have air-conditioning in either of the places we stay at. So we plan we be elsewhere, where possible, on super warm days.

But, in scanning the ten day forecast for our part of the world, there is — as of when I write this — not a single day expected to reach thirty-degrees. The nearest is twenty-eight degrees. Weird, considering January is the warmest month of the year where we are. A surprise La Niña event, kind of, explains the generally lower temperatures.

To be clear though, La Niña, and El Niño weather events do not really influence temperature: they are more indicators of rainfall levels in the northern and eastern regions of Australia. Higher in the case of La Niña, lower for El Niño. But, higher rainfall usually means more cloud cover, which will in part moderate temperatures.

I’m all for not-so-warm summers. Temperatures in the high-twenties aren’t too bad. And providing the dewpoint level stays below twenty degrees, humidity levels aren’t too oppressive either. But I’m not so sure about the accompanying rains, which can result in extreme flooding in some areas.

A La Niña weather event is yet to be officially declared, while the Australian Bureau of Meteorology has moved away making such announcements (probably because people like me write blog posts like this), so we’ll have to wait and see. La Niña, and El Niño weather events however are one of sometimes several concurrent phenomena that influence weather across Australia, meaning certain sorts of weather cannot always be attributed to one particular event.