El Niño is back – what it means for NZ winter | The Front Page

Añadido: 2026-05-06

[00:00:05]Koda. I'm Chelsea Daniels and this is the front page, a daily podcast presented by the New Zealand Herald.

[00:00:15]El Nino is set to hit New Zealand this winter. Global climate models show there's a greater than 60% probability that this event will be strong by spring with the potential to intensify later this year. But what does that all actually mean? What happens when the ocean surface warms and what does it mean for our weather? Today on the front page, Earth Sciences New Zealand and Met Service meteorologist John Tunster is with us to make sense of it all.

[00:00:48]First off, John, and just to preface this by saying I ask this every single time we do something on this subject, but what is the difference between Lania and El Nino?

[00:01:02]>> No, it's a totally fair question. Um, I mean, they're they sound pretty similar to us. They're Spanish words. Um, and they but they are completely different.

[00:01:11]Um, effectively, it is we are talking about a global phenomenon here. We're looking in the tropical Pacific Ocean.

[00:01:18]And El Nino is warmer than normal waters in a certain part of the tropical Pacific Ocean whereas Linia is colder than normal waters in that same region.

[00:01:30]It seems like a pretty small thing. Um but it has uh it initially has local impacts in that area sort of South America and the tropics but those those impacts just cascade around the world very often. How unusual is the speed of this shift from Leninia to El Nino? Does that tell us anything about what's coming up?

[00:01:51]>> Yeah, that's a great question because you know we've been monitoring this potential for quite a while. I would say actually since even the end of last year and you know when you go back and look around there aren't a huge number of uh what we would call historical analoges for a switch that occurs from Laninia to El Nino in the same year and certainly not for one that occurs as quickly as this. So we're really running quite light on analogs to be honest. Um you know when when we sort of searched through the record we were able to find 1976 possibly as one. um and 2023 to 2024 was another one. But the trouble is when you look at these historical analoges, um there's a whole bunch of other variables that change within them.

[00:02:37]So, you know, it can't necessarily be the case that we just follow history and we know what's coming in the future, >> right? So, when we're talking about a potentially strong El Nino, what separates a strong event from a moderate event in in practical terms, I suppose?

[00:02:55]Yeah, it's quite a it we just use a a cutff um which is effectively the um the anomaly of the sea surface temperature in a particular box in the Pacific and when it hits a certain threshold uh that gets counted as moderate or counted as strong and so you know it's quite a binary sort of cutoff um and we it that's just how it's done and it doesn't necessarily mean that uh the impact effects around the world from all strong El Nino are the same or all moderate El Nino are the same. Uh sometimes we can have for example, you know, just a moderate El Nino that has quite a decent effect on New Zealand.

[00:03:35]>> What what is the modeling telling us at the moment? So what should we expect from this change?

[00:03:42]>> Well, we we should start probably looking in the tropics itself because that's that's the thing that's really catching our attention because as it stands, this event this El Nino has not started yet. It's uh it's something in the future. What's interesting is that all of the models that we look at are forecasting uh you know this very dramatic uh increase in service temperatures in that region. You know this consensus is growing and you know we think it's a believable consensus. we we sort of double check these model forecasts up against um what's happening in reality and we can kind of link up sort of known precursors with what the models are saying. So we just want to make sure that we're not looking at something that's in you know what we could say is model land um that it is actually related to reality. So effectively all our all our simulations looking forward are showing a dramatic increase in sea surface temperatures in that part of the Pacific. Now running on from that there will be global impacts.

[00:04:45]Um and the question is where and when do those global impacts occur. Um New Zealand you know we we do like to say we are you know we're just we are a small corner of the world. Um we're expecting this El Nino to have global impacts. It would be surprising if we didn't see impacts on New Zealand from this. Um but there will certainly be places that probably prior to us see impacts. Um you know a great example is that um El Nino tends to uh map quite strongly onto the Indian monsoon um which is a really important global weather phenomenon for producing food for example in India um and the Indian meteorological department have done you know they do a monsoon forecast every year and they're forecasting a deficient monsoon this year. So that's one of the global impacts that we are expecting from this.

[00:05:38]Uh the impacts on New Zealand will probably be somewhere down the line.

[00:05:42]We're actually having our seasonal climate outlook meeting this afternoon when we're looking out to July and we'll start trying to decide when we think those impacts might affect us. It could be during that outlook period or it could be pushed a little bit beyond it.

[00:05:56]That's what we're trying to figure out.

[00:05:59]>> Generally, what does El Nino mean for New Zealand? For us, it's effectively gives us an increase in westerlys. Now, sometimes it's more like southwesterly, sometimes it's more like westerly or northwesterlys, but it's, you know, it's that kind of we're very accustomed to westerly already, of course. Um, but it tends to enhance them, pushes them out for longer, um, can make them more, uh, intense potentially. And what that tends to do is it creates a very particular rainfall pattern in general, which is that uh it focuses rainfall into um western areas and possibly sometimes parts of Southland um depending um and conversely we tend to see, you know, less rainfall making it through to eastern and northern areas. That's the general pattern that we would see um from an El Nino. But it is important to note that um El Nino roughly or I should say the El Nino southern oscillation which is the El Nino and Laninia fluctuations they account for something roughly around 25% of our variability.

[00:07:09]Now 25% of course is um it's not nothing um but it's certainly not everything. So we have this this uh strong driver that's mapping on to you know normally you could say that 25% is up for grabs whereas this time around as this El Nino develops you know that 25% is sort of like more like a baseline that's being covered by the El Nino but there's a whole lot of variability that can take place on top of that >> right so the headline here I suppose with those southwesterly is that we should be expecting a drier winter which someone living in Oakland like myself is is gets quite excited about because I hate nothing more than a an awful wet muggy five seasons in a day. Yes, I said five because Oakland just creates its own season it feels like most times. Um but having a dry winter for separate parts of the country look a lot different. So how does that look on the ground across New Zealand? Yeah, it's um you know it does get a little bit concerning in some areas especially areas you know where primary industries are a very big deal.

[00:08:20]Um you know and what we'll be keeping an eye out for is if things start to already dry out um you know for example the situation weather situation right now is looking reasonably dry for the near future as an example. So, what we'd be concerned about is if we have dryness compounding on top of pre-existing dryness. Um, so, you know, that's where you start to run into uh into concerns.

[00:08:47]Um, you know, it's tricky for places like Oakland because, as I'm sure you're aware as an Oaklander, um there's lots of different types of southwesterlys. Um, you can get pretty blustery, squally, unpleasant southwesterleys, but you can also get southwesterly that are actually they they have a drying trend. You know, they they come they come through and they're not really giving you any showers.

[00:09:12]They're just drying things out. So, there's going to be within a southwesterly um flavor, there's all sorts of little um variabilities that occur.

[00:09:29]You may have seen those scary stories online.

[00:09:32]>> Blow torch El Nino, >> Godzilla El Nino, >> ultra mega El Nino, >> or the even more tame super El Nino.

[00:09:43]Okay, it's time to cut through the hype.

[00:09:45]The truth is there is no such thing as a super El Nino or any of those others, but it sounds really cool and gets lots of clicks on social media.

[00:09:56]How quickly can this dryness, you mentioned dry upon dry, how quickly can that escalate into drought conditions?

[00:10:04]>> That is a Yeah, that's a pretty tricky question because that comes into things like um the baseline of hydrarology. Um, from a meteorological point of view, um, we'd be looking at things like, um, you know, at this time of year, we can we can get dryness occurring at this time of year just from, uh, a lack of rainfall, but, you know, as we've probably all noticed, the uh, the sun is getting weaker. Um, and it's also not a particularly windy time of year. Uh things can get more concerning if we start to we basically if we don't get our winter rainfall or we end up slightly deficient on our winter rainfall and then we come into spring when we have stronger drying winds uh potentially and stronger sunshine.

[00:10:52]That's when we could start to see um concerns. But I think that's somewhere down the line. and it's something that we just need to keep in the back of our minds and um keep up to date with all the latest info.

[00:11:02]>> In terms of the the speedy swing, I suppose from Lan Ninia to El Nino, has this happened more abruptly than in the past? And if so, I mean, you mentioned only a other couple of times in history, but will we continue to see that swing?

[00:11:18]I suppose.

[00:11:19]>> Yeah, it's um I was discussing this with a colleague um earlier. It's I mean, it's another great question. It doesn't appear that we've seen this happen more frequently so far, but there is some quite recent research that suggests that what you're describing there is something that as we push towards later in the century could become um more of a feature of our climate. These that the magnitude of each um El Nino or Lenn event could increase and then the swing is sharper um correspondingly >> in New Zealand. I mean we are kind of in the corner of the world and we do tend to to get news and you know current events and stuff around 3 five years later you know things are trending but is that does that put us in a good position because we can see how El Nino affects other nations like you said India as well so we can see what effect it has elsewhere before it kind of hits us.

[00:12:16]>> That is a good question. Um, I think that we would I think what it allows us to do is we can monitor what's happening with the actual event in the Pacific Ocean, for example. We'll have a direct comparison for how well the forecasts of the actual event have been going against reality. but how things impact on us.

[00:12:37]We're so subject to the southern ocean and all its vagaries that um I would say that um explicitly what happens in India doesn't really have much of a direct impact on us. Um but certainly we we can track the development of the El Nino um ahead of many of the impacts expected on us and that's pretty typical for us. We do see um we're an area that sees a lot of lagged impacts from El Nino. But what I mean by that is that um you know our impacts can be several months down the line sometimes from an event. Uh it's actually happened recently with the Laninia which you know Laninia has actually gone but we've still seen some Leninia type weather patterns. it can be quite tricky for us to kick off uh these patterns >> in terms of I mean we we all know the words right el nino lan nin um we always hear about you know it'll be a dry winter coming up because of El Nino with the oceans etc but what should New Zealanders really look out for like what will they notice >> well I think you kind of touched on it quite nicely earlier you mentioned the type of Oakland weather that you don't like the those muggy muggy wet situations. Um I think that might be a good kind of measure of it that we've talked about this rapid switch around.

[00:14:02]Um so perhaps one, you know, kind of easy comparison is that probably this winter will be different to last winter.

[00:14:12]Last winter was was quite wet for a lot of places. Um there were a decent number of sort of northerly source northeasterly rain events. Um, you know, one good example was the Nelson Tasman flooding that happened late in June or early in July last year. That was sort of characteristic of that type of winter. And I think that what people might start seeing on the ground is that if you've become accustomed to seeing a lot of these kind of humid rainbearing events coming down from the north, maybe we just start start to see far fewer of those uh than what we've become accustomed to in the last year.

[00:14:50]>> Right. So I can hold off another year from not buying a rain jacket >> in Oakland. I have to say that would be uh that would be dare I say slightly foolish.

[00:15:03]>> Thanks for joining us, John.

[00:15:05]>> No worries. Thanks very much for having me.

[00:15:10]>> That's it for this episode of The Front Page. You can read more about today's stories and extensive news coverage at nherald.co.n.

[00:15:20]The front page is hosted and produced by me, Chelsea Daniels. Cain Dicki is our studio operator. Richard Martin, our producer and editor, and our executive producer is Jane Yei. Follow the front page on the iHeart app or wherever you get your podcasts, and join us next time for another look beyond the headlines.