La Niña Spring Update
Prior to the electric telegraph, meteorologists had few tools to forecast the coming weather.
Sometimes signs presented themselves: pre-frontal clouds, red skies in the morning, falling barometric pressure, but without them forecasting wasn't far off guesswork.
This gave rise to an approach to forecasting called the Persistence Method, which could be summarised as 'tomorrow equals today'. Asked what the weather tomorrow will be like, weathermen of yore would describe what they saw out the window today.
When the weather is in a steady state - such as what the Eastern Seaboard has been like the past month or so - it's easy to believe that the weather tomorrow, next week, or even next season will simply follow on with more of the same.
Hence, many people are expecting the Persistence Method to apply to the coming spring and summer - meaning warm and dry.
Unfortunately it won't be the case.
As the Eastern Seaboard continues to dry out under crisp westerly winds and clear sunny skies, it’s hard to imagine that we’re staring down a wetter than normal end to spring and summer. 
Blue skies, clear weather: Enjoy it while it lasts
This year’s La Niña was forecast to arrive much earlier, but the dynamics at play between the ocean and atmosphere took time to develop, though they are finally starting to bear fruit.
Stronger than normal trade winds over the past month have been slowly upwelling cold water across the eastern Pacific Ocean which is now making its way further west. In the image below, the blue 'tongue' of cold water - which is a characteristic of La Niña - can clearly be seen spanning the central and eastern Pacific.
SST anomaly as of 16th September (NOAA)
This development has finally dropped the critical Niño 3.4 monitoring region below the 0.8°C threshold required by the BOM.* If it stays there for three months, La Niña is declared.
The writing, however, is on the wall.
With continued trade-wind activity and a plentiful source of cold water sitting beneath the surface, we can expect this region to stay below thresholds as we round out spring and head into summer.
On paper, it only looks to be a weak La Niña, but as local meteorologists are learning, the temperature of the surrounding ocean - which drives local climate - will also play its part and lift the relative intensity, especially across the coastal ribbon.
What does this mean for Australia?
As cool water surfaces along the equator, warm water is currently piling up across the Western Pacific and Coral Sea and now starting to extend south in the East Australian Current.
All the clear blue water Queensland and New South Wales surfers have seen this last week..? That's the beginning of it.
This will lead to increased convection and rainfall across the north-east of the country, extending down the Eastern Seaboard, with it really kicking in from November.
The below chart shows the precipitation forecast for December to February, with the dark green indicating wetter than normal conditions for much of eastern Australia.
Rainfall anomaly forecast by ECMWF and UKMET for the period December 2024 to February 2025 (Ben Noll Weather)
As for the surf, I think we all know what to expect. If not, cast your mind back to the summers before last.
On the East Coast there was an increase in easterly trade energy as the subtropical ridge shifted south, also subduing the typical north to north-east wind patterns. Local troughiness will likely bring lighter local winds to southern NSW with a slight southerly bias.
In the southern states, swells from a more southerly angle are expected, albeit with less size plus winds from the eastern quadrant - which is good for the exposed beaches.
In the west, it'll make for a summer of clean, hot, but small surf.
Things still have while to play out but we’ll continue to monitor and provide updates on these developments.
// CRAIG BROKENSHA
*NOAA uses a different threshold whilch was reached at the start of the month. Hence US meteorologists calling El Nino/La Nina are slightly out of synch with Australian colleagues.
Comments
Thanks for the update Craig. Bring on the wet spring/summer is say.
Can you please provide the legend that goes with your SST anamoly chart above please.
Yep, here you go Don, all the charts are here as well.. https://coralreefwatch.noaa.gov/product/5km/index_5km_ssta.php
Thanks Craig
I was just thinking how lovely this period without rain has been and reminiscing about the drought years, oh well.
Winds from the east + dead whale = hmmmm
Bring on the tradeswells.
Given the IOD is expected to remain neutral, is it safe to assume that the SAM will be one of the primary drivers as to whether the EC gets drenched or not?
It has been uber dry here on the GC and my lawns are looking a little worse for wear so I cannot wait until Huey brings it down!
Yep, indeed.
So in Adelaide SSW swells and ENE to NE winds?
Hopefully. Likely to be more E/NE mornings compared to the standard SE-S/SE blow.
So as far as south Oz is concerned south swells with south east winds ? Fuck, since the 20219/20 fires that seems like every summer now , shit winds for the south coast , shit swell direction for the mid …
West looks best ….
A bit more easterly bias than true south-east if all goes to plan.
yep. i usually score decent waves when i go back to SA for christmas/summer. these last few years have been... THE WORST. SW/SE winds and almost no groundswell. brutal.
the only time i've scored waves there in the past 4-5 years is the easter break and the obligatory massive storm swell that seems to land around that time.
But as Nick points out, it's the swell that will be the problem.
Cheers Craig , appreciate your work
It’s summer - the cycle stays relatively the same.
What is going on at present down here in Victoria is miles from La Nina. Giant swells every couples of weeks with persistent solid swells in between, and west winds blowing a gale. Haven't got near the beaches since I don't know when and who knows what the banks will be like when it finally abates. I've even regressed to surfing WP which is tragic. Are you saying that it will be a gradual break from this or it will happen quite abruptly?
sounds good for consistent waves in the Sydney region?
i feel like these last few la-nina summers have been way above par with actual swell and very few days of 2 foot/6 sec NE windswell.
I can’t remember the Summer before last…so for Manly, we’re looking at a wet start to Summer with onshore winds and not much swell….is that about right?
Pete, Craig might correct me, but it's more along the lines of fewer blue skies, more rain, less NE seabreezes, and fairly consistent easterly tradeswell, punctuated by the odd bigger swell also from the E/NE.
Unless you're into sunbaking, I reckon that's a good outlook.
Phew, I wrong that read then
Yep Stu nailed it. More cleaner days than a usual summer at Manly but with less north-east windswell events and more so longer range east-northeast trade swell.
Nooooo. Not again. Another summer of hectic sidewhore winds.
This is terrible news Craig.
Off to the naughty corner for you!
I can't remember what i did yesterday, I got no chance of remembering what happed 2 summers ago. Was it good?
4 summers in a row of absolute junk down here. Hard to erase from the memory unfortunately. :(
What does this mean for the few weeks around late July/early August 2025 on the Mid North Coast of NSW?
PS - taking the piss.
Yeah nah, but seriously?
All that signals another super consistent summer of b-grade trade-swells for the sub-tropics- which is great. Surf every day in warm water.
Been some interesting natural signs around the last month. Despite a truckload of northerlies and green water (usually cold upwelled water) the inshore SST's have remained fairly warm- which has to be a signal from the EAC responding to the active trade-flow.
Tuna have been regularly caught inshore in the last 2 months, which is another sign of an active EAC, and unseasonal for Aug/Sep.
This morning I watched a full bust-up from long tail Tuna just out the back of the break.
Everything looked spring-like with the S swell and N winds except the water was blue and tuna were busting up in it.
Let's just hope the Northern Rivers gets spared another catastrophic flood.
what r the chances of "dear diary " greenmount episode 2. was my fav article in the last year(:
Almost time for my yearly lap of the Superbank.
VG (:
Thanks Steve very informative.
I personally took on that dare I set you about surfing in boardies after the week of northerlies!.. still so warm... I can't recall a time when the northerlies didn't drop the temps.
Haha I experienced that as well!
Northerlies kicking in a month earlier this year I reckon
Seasons are out the window.
We had a heatwave in August.
Blowflys, bushfires & Total Fire Ban days have arrived in Sept. Ocean 20C.
Its so hot & dry now, all the snakes are moving down the gullies looking for water... & nookie.
Offshore & long period winter south swells in spring..
with furious fifies roaring up into the fourties & beyond. Batten down the hatches Tazzie folks.
ECL next weekend
https://www.weatherzone.com.au/models/charts/gfs/aus?chartCode=prmsl_thk...
Sounds like Feb / March rain may shift forward to December. The bush and garden needs a drink.
Cyclones in January?
https://www.ausstormscience.com/tropical-cyclones/historic-tropical-cycl...
thanks Craig, your analysis is so clear and digestible. I was wondering why one day we had mucky cold water and the next back to clear aqua and warmer.
great can't wait, I surf beaches so onshore is fine, but the brown water......why don't we have a wave pool in qld
The BoM spectacularly got it wrong last spring - forecasting the mother of all El Ninos - a Hot dry summer they said , massive bushfires season they said , drought up and down the east coast they said ....
and we all know how that turned out !!
And that El Nino forecast was on the back of some very strong signals coming out of winter last year .
point is - forecasting 3 to 6 months in advance is not reliable , particularly with such radical climate change as we are experiencing now days
" Stick to 7 days BoM - you're good at that " , : )
This is correct, to a degree. We were in El Nino last spring/summer, however it was largely offset by warmer than normal ocean temps.
The same thing appears to be happening again - all NSW buoys are currently above their seasonal average - however the effect of that, more rainfall, is in lockstep with the effect of La Nina.
Of course, there may be something chaotic and unknown arise between now and summer.
Fortunately surfers don't have to sell stock or plant seeds according to weather forecasts.
Some of us do Stu ! , and some of us , on the back of quite definitive forecasts from the BoM , sold livestock (at heavily reduced prices ) on the advice of a coming El Nino last year . Point is - 3 to 6 month forecasts , because there are soo many variables involved , should really be the realm of soothsayers and and druids , and not be taken too seriously by those of us that rely on the weather for a living !
Mid North Coast NSW had lowest recorded rainfall for Jan to Oct 2023 and the fires had kicked off, so the BOM were on track with the El Niño forecast …. Until the storms came.
Right, I should take that back then!
Tough situation when having an accurate long range forecast affects your business.
All good Stu !
Actually you would be mad to be basing business decisions on long range forecasts . They are just not reliable enough and last years dodgy El Nino forecast proved that beyond doubt !
As long as it’s not a summer where the wind is a constant s/e, without even a morning n/e I’ll be happy
Here's the latest Niño 3.4 readings..
So if it dipped under zero in mid-July, the BOM will call it in mid-October, provided it stays below?
Not quite.
The BOM's threshold is 0.8°C while NOAA's is 0.5°C so we'll see NOAA call it before the BOM.
Current run of S ground swells in VIC and now NSW partly due to the stratospheric warming and then La Niña is just going to take over?
Water was so clear on the reefs over the last few days.
The last large run of swell was from the Stratospheric Warming event but the drivers behind it have since dissipated.
This one is now a response to a strong MJO signal in the Western Pacific. Discussed more here: https://www.swellnet.com/forums/the-crystal-ball/592487
Gotcha, I live in one of those NSW south swell spots though (which funnily enough tends to like it when bells is good)..
Always thought that the MJO was more of a forecast for winds/precipitation in more tropical latitudes but apparently (like everything else) it’s more complicated.
No you're correct, it's an indicator for increased precipitation and cyclone potential, but when strong enough it also forces the mid-latitudes by teleconnection. That being in the form of could outbreaks across south-east Australian when the MJO is in the western Pacific Ocean.
Does the increased moisture mean more thunderstorms for NSW? Or will the weather be more settled (i.e., more cloudy days with weak southerly wind)?
Thunderstorms are more related to atmospheric instability than actual moisture content. Last few summers in Northern NSW have been very wet but without much t'storm activity.
Ben nailed it. Especially with the lack of heat build up from inland from wetter, cloudier days = less temperature gradient and TS potential.
Thanks for the responses! Looks like I'm going to have to find new things to photograph. Or just move to Darwin.....
http://www.bom.gov.au/climate/averages/climatology/thunder/explain_td.pdf.
I have considered holidaying to Darwin for storm chasing - getting a motel room with an elevated balcony to photograph/video from and/or car hire added.... from what I've observed storms are most common over Tiwi island. Quite a lot of days have storms inland from Darwin - Humpty Doo, Batchelor etc while storms over Darwin itself are less common. I don't know how many roads become impassable in the wet season, peak storm viewing would be November/December while Jan/Feb are more rain....
What general area are you in? and do you storm chase to other regions?
I'm in Sydney. And no I'm not that adventurous. I don't chase storms, just hope they come my way a few times. There are some great spots up in the blue mountains where I have watched them roll in and then you can watch them for hours as they move over sydney and out to sea. Great viewing. Sydney only averages 15 - 20 storm days a year though, so it's awesome when it comes. Just have to do a lot of waiting.
Hector the thunderstorm and he emerges every day around 3pm. If you want to meet him you’ll need to travel to the Tiwi islands, around 70km north of Darwin, Australia, during the build-up season (September to December) or rainy season (January through to March). Hector is so reliable that locals set their clocks by him.
La Nina seems to produce an above average number of storm days in southern NSW - at least during spring (when we often struggle to have enough moisture depth in El Nino years). The risk of La Nina would be too much rain and cooler weather, particularly in summer.
Converging winds are ideal for triggering storms, so fingers crossed for lots of days with moist E/NE winds pushing out to the tablelands meeting warmer, drier winds inland.
Can anyone tell me if La Nina will affect the wind direction/strength higher up in the atmosphere - particularly at the altitude for steering winds for thunderstorms (500-700 Hpa)?
We seem to have the opposite here in NENSW.
Less storm days in traditional Spring/early Summer season during La Niña.
Storms appear randomly late summer/autumn even early winter.
Potential for alot of brutal months for those in the construction industry in East northern New...... Queensland.
Not a good forecast for those on the tools
Another biological indicator of warm water and EAC flows seems to be changes in shark species.
We often see big Tigers show up with EAC surges ( there was a submarine hanging around Lennox Point last summer).
DPI Fisheries advise: tagged Tiger Shark #2144 detected by Ballina receiver at 10:40:59 PM (AEST) on 19-September-2024. Last detected at 10:20:58 PM (AEST) on 19-September-2024 by Ballina receiver.Tagged and released 27-February-2024(AEDT) at Main Beach line, Evans Head.
Tigers hunting on the North Shore atm.
Tiger season is never a good season
Could keep the juvey white numbers at bay though ? Food for thought.
I’ve often wondered if tigers and whites have much contact with one another?
I'll ask my son , he's a complete shark nerd
Has so many facts about things like that.
Please do
Can’t say there’s much I like about La Niña summers. There’s only two spots on the Sunshine Coast that handle the conditions associated with them. La Niña would have made for some enjoyable summers of surf 30-40 years ago but with the population being what it is now, well, looks like I’ll be doing a lot of muddy mountain bike rides.
I agree with some of the sentiments expressed on here, it really is difficult to know what to expect out of climate drivers such as La Niña given the changes going on due to the background warming of the climate. Perhaps it was a result of that sudden stratospheric warming event, but I’d say that the records set last August would have been statistically so unlikely, that it would be difficult to predict such an anomalous month using any of the known climate drivers. In short, I think an early onset La Niña summer will probably throw up all sorts of unexpected weather.
Can remember the frustration of being confronted with the SC onshore whilst seeing the nth goldy was light south and southern goldy/nthNSW offshore!
I used to embrace the onshore. Hey, at least you’ll have swell.
Thanks for the update Craig.
I’ve hardly even bothered with my little daily surf report for the last couple of months because it’s been so bland.
I’d be interested to know what’s happening with the strength of the east coast current(s) over the last few years.
I'll try and dig out something.
Thanks
Re: “ In the west, it'll make for a summer of clean, hot, but small surf.” Bloody hell.. that’s not good news for us Surfers around Perth & Mandurah… looks like down south will as usual be the only option over summer.
Cheers Craig, good summary. Does El Nina have any effect on the Indian Ocean Dipole?
A negative IOD usually follows La Niña years thanks to the elevated sea levels linked to the warm water in the western Pacific being higher than that in the Indian Ocean, causing a through flow.
A bit more on that here: https://www.swellnet.com/news/swellnet-analysis/2022/05/05/wet-and-wetter
Hi Craig, when there’s La Niña here in Aus what does it typically mean for Central America, El Salvador in particular? I’m stopping by there in December and curious to know what to expect.
Please say more South swells
Having a quick, rough check of the pressure anomalies across the South Pacific and Southern Ocean, it does appear to bring an increase in southerly energy thanks to lower than normal pressure along the polar shelf between New Zealand and South America.
Cooler water but.
Thanks Craig! Much appreciated.
Thanks for the climate & waves update Craig.
&t=22sThe earth & oceans systems try to rebalance.
Northern hemisphere water is very warm atm.
https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/daily/png/ct5km...
https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/animation/gif/s...
Good time to landscape with tropical plants on the east coast; bananas, sweet potato & pawpaw.
Pacific Islands climate info below.
just went back through my archives to see what it was like a couple summers ago and if it turns out anything like that then I'm excited!
What are your thoughts on the east coast of the NZ north island?
There was recently some days with fresh offshore winds;
Fresh easterly, nor east going north then back ne,
My favourite local spot had its day and best of all there was no internet pro filmers there
, which has become rare !