SoCal Forecast
Updated most Sundays, Tuesdays, and Thursdays

Thursday 9/17/26 6:40 AM
By Nathan Cool

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At a glance:
Today (Thursday the 17th) we have moderately sized southern hemisphere ground swell in SoCal with minimal NW wind swell. Smaller surf is on tap for the weekend although light southern hemi builds Sunday the 20th, peaking with better size a couple days later. Light to moderate NW ground swell is being watched for the second half of next week. Strong NW wind swell is being monitored for the 26th-28th. We may see moderately sized WestPac Typhoon swell in the mix around that time. And I've included more info on the developing El Niño. Condition-wise: fair weather with some day-to-day differences in marine layer and cloud cover; winds trend onshore; tide levels are fair; and water temps are up in many spots.

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Current Conditions:
Early this morning, periods were primarily running 17 seconds from 195° and 9 seconds from 315°.

Most south facing breaks were running chest high with occasional pluses at breaks working refraction from the San Diego Trough (page 111). Some south facing spots affected by shadowing were running waist to chest (page 81). Direct west facing spots were mostly waist high.

Buoys in the outer waters were running 4-5'. Nearshore buoys were averaging 2'.

Tide levels are running at moderate levels right now. Today we have a 3' high around 5:00 AM, a 4.7' high around 1:00 PM, and a 1.2' low around 10:30 PM.

Water temps were running 73-76° around most of SD and OC. LA was mostly 71-75°. In VC, Channel Islands Harbor reported 72° last night. SB Harbor reported 70° this morning.

Surf Forecast:
Today (Thursday the 17th) we're reaching the peak of the southern hemi ground swell from this system that was south of French Polynesia last week (model generated by XyGrib from NCEP data):

This swell should linger Friday the 18th with similar size and then back off Saturday the 19th to about waist high at south facing breaks.

NW wind swell remains minimal. In fact, the wind swell for the weekend got another downgrade with not enough outer water winds to kick up much more than waist max waves at west facing breaks Saturday the 19th and Sunday the 20th. Fading southern hemi should provide similar size both days; however, Sunday should see a slow building trend in southern hemi.

Sunday the 20th (building day) into Monday the 21st should see SW ground swell start to build from this activity that was near New Zealand about a week ago (model generated by XyGrib from NCEP data):

Although that particular fetch was located south of New Zealand, which blocked a good amount of its swell, it did reform and move northward to send us something better for the 22nd-23rd (model generated by XyGrib from NCEP data):

This should result in initially waist high waves at south facing breaks Sunday the 20th and Monday the 21st, increasing to waist to chest Tuesday the 22nd, and then chest high Wednesday the 23rd. Swell should be angled from 215-220° with periods 16-17 seconds. This swell should continue with chest high waves Thursday the 24th, which may not be the only swell in SoCal then.

Thursday the 24th could see an early season NW ground swell from this system in the Gulf of Alaska on the 3-day models (model from NOAA OPC):

Its 20-25' seas are at the upper end of the forecast. But with the deterministic models pointing in that direction, confidence is high enough to make an early call for waist to chest high waves at west facing breaks Thursday the 24th, angled from 305° and periods 14 seconds. I'll be able to confirm this in my next report (Sunday).

Saturday the 26th through Monday the 28th could see robust NW wind swell in SoCal as this hefty, and rather windy trough of low pressure (red circle) pushes south into SoCal (model by NOAA MAG):

This was upgraded on the models today with enough wind to produce wind swell waves in the head high range at west facing breaks. This though is on the 8-day-plus models, making it too early to call. Another item on the model, btw, is circled in blue: two tropical storms that could move northward to send southerly swell to SoCal, arriving around the 28th. I won't venture into those systems as they're highly questionable this far out. The trough/wind-swell, having jetstream guidance, is a safer call — so far.

Monday the 28th, along with NW wind swell, we might also see intermittent sets from TS Dujuan in the Western Pacific, which would take a retrograding course back out to sea, sending us at least a glancing blow of swell energy (model generated by XyGrib from NCEP data):

This is on the 5-day outlook with the juicy purple center representing 38' seas. It's a good 4,400 nautical miles from SoCal, which would have a good deal of distance decay (page 51). And although that model's flat projection may appear to have the storm lined up near SoCal's latitude, it wouldn't be; instead, it'd be angled from around 300°. Its course also means a fair amount of angular loss (page 52). So running the numbers, this works out to spotty, chest+ waves at west facing breaks Monday the 28th, angled from 300° and periods 18 seconds. It's actually quite common for WestPac typhoons to take these retrograding courses as they get caught up in the North Pacific Gyre (see illustration on page 146). Still, this is on the 5-day, and NW wind swell may meet or exceed size from Dujuan on the 28th.

Tuesday the 29th is the next swell on my charts from this impressive southern hemi with an unfortunate course (model generated by XyGrib from NCEP data):

Much of its energy would be blocked by New Zealand, but its 35'+ seas would be enough to produce waist high waves at south facing breaks, angled from 225° and 18 seconds. Models have bandied about this for days with some scenarios this morning (ECMWF in particular) showing a lasting portion of its fetch holding together on the east side of New Zealand, which would send us slightly better size. I'm not counting on it but I'll firm that up in my next report.

Looking out on the longer range, I thought it might be useful to put this year's El Niño into perspective to show what's different now from El Niños of the past. As you might recall, the "Godzilla" El Niño of 2015-16 did in fact have a stronger "signal" than the 1997-98 El Niño, but the 2015-16 event brought much less rainfall. The 2015 event brought heavy and very large surf, at least for December. For rain though, the 2015-16 Niño was disappointing. For instance, the 1997-98 rain-year received over 30" of rain in LA but the 2015-16 rain-year got a mere 10". Why that might be is the point of interest I wanted to quickly touch on before getting to the rest of the report.

Right now, all remains on track for a strong El Niño, peaking in a couple months (image from NOAA CPC):

NOAA gave this a slight upgrade last week with the mean strength (black line) peaking in October, November, December (OND) at about 2.6°C. By comparison, the El Niño of 2015-16 measured 2.6°C, and the 1997-98 Niño was 2.4°C. So this year's El Niño might meet or exceed those events' signal strength. Rain is a different story, but so are the water temperatures across not just the El Niño zones (where the signal is measured) but across the entire Pacific, and our planet as well. For instance, here's what the water temps looked like leading up to the 1997-98 El Niño (model from NOAA Coral Reef Watch):

In these older models, the Pacific wraps from the left to right side of the image, different from more recent models that'll show for comparison. In any case, we can see the telltale red tongue of warm water extending off Peru (left side of the image), signaling a strong El Niño. But notice all of the blue water in the North Pacific, which represents below average water temps. This is much different when we look at the water temps leading up to the "Godzilla" El Niño of 2015-16 (model from NOAA Coral Reef Watch):

Sure, we see the telltale tongue of warm water extending off Peru (center of this image), but notice what's absent: blue, colder water elsewhere in the Pacific. In fact, the North Pacific is dominated by marine heat waves, — coined "The Blob". Overall though, with the North Pacific being so warm in 2015 there was less difference between warmth in the El Niño zones and the rest of the North Pacific.

If we take a look at the present state of El Niño, we see something similar (model from NOAA Coral Reef Watch):

El Niño warmth is evident off Peru. But waters are exceptionally warm in the North Pacific too. If we put a measurement on this difference, the 1997-98 event was about Δ4°C but today the difference is about Δ2°C. But that's just one aspect to consider.

A strong El Niño signal like we're seeing now is not to be taken lightly. And no two El Niños are ever the same either. Instead, the 2.6°C forecast for this year's El Niño is a warning to make immediate preparations. But no one can say with a high degree of certainty if this winter will be similar to 1997-98, 2015-16, or other El Niño seasons. If this year's event turns into a repeat of 2015-16, then we'll learn, adapt, and correct. For good reason.

The Pacific is the largest single physical surface feature on a planet that's spinning over 1,000 mph while racing around a modest star at a blinding 67,000 mph within an insignificant solar system housing a handful of planets traveling through a galaxy at 514,000 mph that's traveling through a universe at 1.3 million mph. To think that we — as relatively new creatures residing on this water-filled rock hurtling through space — can predict with any level of accuracy what will happen within its chaotic system of weather, especially months out, is not (yet) within our grasp. But what we can do is to monitor, prepare, and progress our understanding. After all, our species hasn't perfected science — we're building on discoveries of the past to provide better understanding for future generations to develop further as we pass the baton to them from what we learn today.

Our world of weather and waves is a constantly moving target. All of this needs much more monitoring in the coming weeks and months. But as long as I have your support then I can continue to keep an eye on the Pacific to keep you posted. Please remember this report is funded by reader donations and your help is vital to keep it alive (see why here).

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Here's a brief look at how the next few days are breaking down so far:

Friday the 18th looks about waist to chest at south facing breaks, smaller at west facing spots.

Saturday the 19th should run waist high at most spots.

Sunday the 20th should run waist high at most spots.

Monday the 21st should run waist high at most spots with occasional pluses at standout south facing breaks.

Tuesday the 22nd looks about waist to chest at south facing breaks and waist high at west facing spots.

Wednesday the 23rd looks about chest high at south facing breaks and waist high at west facing spots.

Thursday the 24th, so far, looks about chest high at south facing breaks and waist to chest high at west facing spots.

Friday the 25th, so far, looks about waist to chest high at most breaks.

Saturday the 26th may see notable NW wind swell...more on that in my next report.

 

Weather Outlook:
Today (Thursday the 17th) we're in a mild weather pattern that will shift ever so slightly now through most of next week as minor troughs of low pressure are interspersed by weak ridges of high pressure. One low pressure trough is sagging into SoCal today, keeping an onshore flow in place with a good deal of marine layer through Friday the 18th. A weak high moves in Saturday the 19th for slight warming and earlier clearing. But then a trough moves in Sunday the 20th, bringing not just marine layer but high clouds too. Weak high pressure backfills the passing trough early next week before a very robust trough digs into SoCal by the weekend of the 26th, shown here again to save you from scrolling (model by NOAA MAG):

The tropical storms (blue circle) are worth watching. But the trough looks like the main feature with a notable onshore flow, no precip, but much cooler temps and plenty of wind.

Taking all of this into account, here's how I'm calling SoCal beach weather for the next few days:

Today (Thursday the 17th) should see a burn-off by noon and max beach temps in the low 70s.

Friday the 18th should see AM marine layer with a burn-off around mid to late morning and max beach temps in the low 70s.

Saturday the 19th should see AM marine layer with a burn-off around mid to late morning and max beach temps in the low 70s.

Sunday the 20th should see AM marine layer with a burn-off around midmorning but high clouds should drift overhead for a good part of the day. Max beach temps should reach the low 70s.

Monday the 21st should see AM marine layer, burn-off by early afternoon, and max beach temps in the low 70s.

Tuesday the 22nd should see AM marine layer, burn-off by noon, and max beach temps in the low 70s.

 

Wind Outlook:
Winds at 7:00 AM light and variable most everywhere with a southerly element. Afternoon onshores should run 15 mph.

Friday the 18th should see AM light and variables and afternoon onshores to 15 mph.

Saturday the 19th should see AM light and variables and afternoon onshores to 15 mph.

Sunday the 20th should see AM light and variables and afternoon onshores to 15 mph.

 

Until my next report (Sunday), take care, be safe, and smile in the lineup!

—Nathan

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