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Pacific Storm and Surf Forecast
Updated: September 21, 2010 8:02 PM
Buoys: Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Buoy Forecast:
Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Pacific Links:  Atmospheric Models - Buoy Data - Current Weather - Wave Models
Forecast Archives: Enter Here
A chronology of recent Mavericks Underground forecasts. Once you enter, just click on the HTML file forecast you want to review (e.g. 073199.html equals July 31, 1999). To view the maps that correspond to that forecast date, select the html file labeled 073199 maps.html
Swell Potential Rating = 3.0 - California & 3.0 - Hawaii
Using the 'Summer' Scale
(See Swell Category Table link at bottom of page)
Probability for presence of largest swells in near-shore waters of NCal, SCal or Hawaii.    
Issued for Week of Monday 9/20 thru Sun 9/26
Swell Potential Rating Categories
5 = Good probability for 3 or more days of Significant swell
4 = Good probability for 1-2 days of Significant swell
3 = Good probability for 3 or more days of Intermediate/Advanced swell
2 = Good probability for  1-2 days of
Intermediate/Advanced swell
1 = Good probability for 3 or more days of Impulse or Windswell
0 = Low probability for 1-2 days of Impulse or Windswell   

Another Small Dateline Swell Pushing to California
Models Hint at A More Active Pattern to Come


New Swell Classification Guidelines (Winter)

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead). Summer - Head high or better.
Advanced: Winter - Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft) Summer - Chest to head high.
Intermediate: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft). Summer - Waist to chest high.
Impulse/Windswell: Winter - Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs. Summer - up to waist high swell. Also called 'Background' swell.

On Tuesday (9/21) North and Central California was getting the trailing edge of northern dateline swell generated over the previous weekend encased in local northwest short period windchop and pretty much unrideable.  Southern California was getting waist high northwest swell up north and clean.  Down south the northerly swell was shadowed with fading southern hemi swell in the thigh high range and clean.  Hawaii's North Shore was still doing well with shoulder to head high sets and pristine conditions. The East Shore was getting wrap around energy from the North Shore at chest high with lightly chopped conditions. The South Shore was effectively flat and clean.    

The forecast for North and Central CA is for local short period northwest windswell at 3 ft (faces) on Wednesday and fading, down to near flat on Thursday.  Friday swell from the dateline to build to maybe 4.5 ft later with maybe a little more north swell arriving after dark. Saturday north swell to be fading from 5 ft. Southern California is to see nothing rideable on Wednesday through Friday. Maybe some waist high north swell at select breaks on Saturday. The North Shore of Oahu is to see more the last of the sideband dateline swell fading from thigh to waist high early Wednesday.  New dateline swell arrives for later Thursday at 1-2 ft overhead holding at 1 ft overhead on Friday then dropping from shoulder high early Saturday.  The East Shore is pretty much off our radar screen now that a Fall Pattern is setting up.  The South Shore is to see no rideable surf till Thursday when swell from the Tasman Sea filtered by Fiji arrives at shoulder to head high early and holds at nearly head high Friday then dropping from chest high on Saturday AM and waist high Sunday AM.   

Up north another small early season gale formed on the intersection of the dateline and the Aleutians Sunday evening into Monday (9/20) with seas initially in the 28-30 ft range, then fading.  Swell arriving in HI on Thurs and NCal on Fri (9/24).  Remnants of this system are to reorganize off Vancouver Island on Wed/Thurs (9/23) with seas to 26 ft, with yet a larger system forecast for the Central Gulf of Alaska Thurs-Sat (9/25). And yet more is expected behind that in the Central Gulf  early next week with another behind that int he Northern Gulf mid-week. Looks like the models think Fall is coming.  

Down south a gale tracked into the Tasman Sea Thurs AM (9/16) with seas to 38 ft and slowly fading into Saturday AM with seas dropping below 30 ft, all focused very well on Fiji and Northern New Zealand, with limited energy expected to filter through Fiji reaching Hawaii on Thurs (9/23) with less for California maybe by Sun (9/26).  But with the North Pacific expected to get active, this is becoming much less of a priority. 


Current marine weather and wave analysis.cgius forecast conditions for the next 72 hours

North Pacific

On Tuesday (9/21) the North Pacific jetstream was pushing flat off the Central Kuril Islands with winds isolated to 160 kts there, then tracking east on the 45N latitude reaching to the dateline before dipping slowly southeast with a weak trough over the Western Gulf of Alaska (winds 120 kts) and a steeper one just off Central CA (110 kts). Limited support for gale development was possible in both troughs. Over the next 72 hours the Kuril wind energy is to start pushing solidly east pushing over the dateline on Wed (9/22) with winds up to 170 kts and organizing into a broad trough there falling into the Gulf of Alaska and deepening. Good support for gale development possible n the Gulf of Alaska then. Beyond 72 hours more wind energy is to be building over the West Pacific ridging over the dateline then falling into the building trough in the Gulf through Saturday (9/25) looking very nice with winds 150 kts providing good odds for more gale development there. That trough is to steepen and ease east through Monday (9/27) while the jetstream falls down to 40N off Japan and things settle down some, but not out completely. This certainly looks like a Fall pattern might be starting to set up.   

At the surface on Tuesday (9/21) remnant low pressure from the dateline gale (below) was moving from the Bering Sea to the southeast with residual 20-25 kt northwest winds blowing over the Western Gulf of Alaska, though not strong enough to produce swell of interest. More low pressure was just inland of the Kuril Islands. Otherwise weak but broad high pressure at 1020 mbs was anchored over the southern dateline ridging east to just off the CA coast generating 15 kt north winds there but having no real effect on trades over Hawaii. In short, no swell producing fetch was occurring, but the pattern was vastly improved from even a week ago. Over the next 72 hours remnants of the dateline gale are to reorganize about 800 nmiles west of Vancouver Island Wed AM (9/22) with pressure dropping to 992 mbs and winds to 40 kts over a tiny area at 49N 148W while tracking slowly east. This system is to hold strength into the evening with 40 kts winds at 48N 142W  and seas building 26 ft at 48N 142W  and holding that size at 26 ft at 48N 137W by Thurs AM.  Both these reading to be on about on the 312-316 degree track to NCal but focused better on the Pacific Northwest. Remnants of this gale are to push into Vancouver Island on Friday AM with decent sized 13-14 sec period raw swell pushing into the Pacific Northwest during the day Friday. If this occurs some small push of 13-14 sec period rideable swell could reach Northern CA by Friday well after sunset and be fading into Saturday AM (9/25). 

At the same time a new broader gale is forecast developing over the Western Gulf on Thursday AM (9/23) with pressure 972 mbs and west winds to 40 kts building at 48N 170W with seas building from 23 ft. By evening up to 45 kt northwest winds are forecast at 47N 163W  on the 298 degree path to NCal and aimed 40 degrees east of the 353 degree path to Hawaii with 30 ft seas forecast at 47N 164W.  Friday AM (9/24) 40 kt west-northwest winds are to drop to 45N 153W on the 297 degree path to NCal and pretty much east of the Hawaiian swell window with 34 ft seas at 45N 157W. Friday PM winds are to fade to 35 kts but making more southeastward progress at 42N 150W generating 31 ft seas at 42N 152W (294 degs NCal).  A quick fade is forecast thereafter.  If all this comes to pass the first real legitimate utility class swell of the Fall season is forecast pushing into Hawaii and Northern CA. Will monitor.    

Another Dateline Gale
On Sunday AM (9/19) a new gale built just south of the Aleutians and west of the dateline off Kamchatka at 976 mbs with west winds 40 kts at 50N 170E aimed well up the 308 degree path to Central CA and 30 degrees east of the 327 degree path to Hawaii. Seas were building from 28 ft over a tiny area at 51N 172E. This held into the early evening with seas peaking out at 31 ft at 50N 176E, then faded some as winds dropped to 35 kts Monday AM (9/19) and seas faded from 30 ft at 50N 178W.

Some degree of small northwest swell is likely building into Hawaii on Thursday (9/23) pushing 4.5 ft @ 14 secs late (6.5 ft faces) holding at 4.8 ft @ 12-13 secs on Friday (6 ft faces) then heading down by Saturday.  Swell Direction: 325-330 degrees  

Central CA
is to start seeing swell from this system Friday (9/24) pushing near 4 ft @ 15 secs mid-day (6 ft faces) and then fading into the early weekend. Swell Direction: 308 degrees


North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height


On Tuesday (9/21) a tropical storm with sustained winds at 35 kts was located 180 nmiles north of Saipan or roughly 1200 nmiles south of Northern Japan. The models suggest it is to slowly organize while tracking north reaching hurricane strength late Thursday and then turning on a north-northeastward track for Friday while intensifying, racing towards open waters just off Kamchatka on Sunday (9/26). The models depict it moving into the Bering Sea, then turning southeast and falling into the Western Gulf of Alaska by Tues (9/28) with a broad fetch of 35 kt northwesterly winds. It's way too early to believe any of this just yet, but is something to monitor. 

California Nearshore Forecast
On Tuesday (9/21) a weak ridge of high pressure was trying to reach into California waters setting up a generalized 15-20 k northwest windflow nearshore over North and Central CA making for chopped conditions, but not strong enough to produce real windswell. This high is to try and hold on into Wednesday as a series of gale lows start building and moving into the Gulf of Alaska.  The net result is those northwest winds and the local pressure gradient are to be eroded some Thurs - Fri (9/24), but are to not totally dissipate, resulting in steady northwest winds at 15 kts mainly over outer waters, and less nearshore. Probably still a good bit of warble left though. By the weekend the high is to be almost gone with more low pressure building off the coast, but starting to return by Tuesday (9/28) as low pressure relents. Southern CA is to remain mostly calm other than perhaps Wednesday.  San Francisco southward to get a break starting in the mornings on Saturday.  


South Pacific

On Tuesday (9/19) a broad trough was under New Zealand with 120 kt winds feeding up into it offering decent support for gale development there, then falling into a solid ridge over the eastern half of the South Pacific and shutting down gale development potential there. 
Over the next 72 hours the trough in the west is to slowly moderate and flatten out with no support for surface level gale development suggested.  Beyond 72 hours a ridge is to build over the West Pacific reaching down to Antarctica, while a new trough builds over the East. But winds speed are to be light feeding up into that trough offering little to support gale development at the oceans surface.

At the oceans surface on Tuesday AM (9/21) a gale low continued tracking under New Zealand (see Another New Zealand Gale below). Otherwise high pressure at 1032 mbs had a lock on the Southeast Pacific offering no fetch of interest.  Over the next 72 hours a series of 2 gale are to develop just southwest of New Zealand and push directly into land there, with nothing of interest forecast to survive the impact and leach out into the Southwest Pacific. 


Tasman Sea Gale
At the oceans surface on Thursday (9/16) a broad gale built in the Tasman Sea.
This system started forming south-southwest of Tasmania on Wed (9/15) with 45 kt south to southwest winds pushing mostly into Tasmania, with maybe a little reaching clear of it's south end and tracking up into the extreme southern Tasman Sea. On Thursday 40 kt southwest fetch was finally pushing free and clear of Tasmania reaching to 39S 152E early and up to 36S 165E late resulting in 37 ft seas at 39S 159E (Thurs PM).  Then on Friday additional 40 kt southwest fetch built into the Central Tasman Sea near 40S 160W resulting in 33 ft seas at 40S 170E in the evening. This system faded fast on Saturday AM. Northern New Zealand is to receive the brunt of this swell though an almost equal amount of swell energy is to push up into Fiji starting on Sunday AM (9/19 GMT).

Filtered swell is expected to hit Hawaii late Wed (9/22) at 1.6 ft @ 18 secs at sunset (3 ft faces) building overnight and pushing to 3 ft @ 16 secs (head high to 1 ft overhead) late Thursday (9/23).  Swell to hold at 3 ft @ 16 secs (head high) on early Friday (9/24) then slowly settle down. But still swell of 2 ft @ 14 secs (waist high sets) is expected on Sunday (9/26). Swell Direction: 215 degrees.

Dribbles are forecast pushing into Southern CA on Sunday (9/26) at 1.6 ft @ 18 secs (2.5 ft faces) reaching 2 ft @ 16 secs (3 ft faces) on Monday.  Swell Direction: 231-235 degrees.

Another New Zealand Gale
A new storm wrapped up south of the Tasman Sea Sunday evening with 45-50 kt south winds at 56S 155E aimed directly at New Zealand. This fetch lifted northeast and starting to impact the southern tip of New Zealand Monday AM (9/20) with the core still at near 50 kts at 53S 160E (southwest of New Zealand). By evening the fetch was still at 45 kts located at 54S 168E moving into the 220 deg swell window for California. 32 ft seas were modeled at 50S 170E, perhaps pushing energy towards CA. Tuesday AM (9/21) a tiny fetch of 45 kt south winds persisted at 52S 170E resulting in near 32 ft seas at 50S 172E over a moderate area and pushing up the 216 degree path to California and unshadowed by Tahiti and the 200 degree path towards Hawaii. The fetch is to be gone by evening with sea to 34 ft from previous fetch at 50S 179E. It seems reasonably to assume that a decent little pulse of southern hemi swell will radiate towards Hawaii and California, with the Islands getting the better shot of the energy just due to being closer minimizing swell decay. But with swell from the North Pacific becoming more of a reality, this swell becomes less interesting.

Expect swell arrival in Hawaii starting Tues (9/28) with swell 2 ft @ 17 secs (3.5 ft faces).  Swell Direction 198 degrees.


South Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height




Marine weather and forecast conditions 3-10 days into the future

North Pacific

Beyond 72 hrs yet another low pressure system is to moving from the northern dateline region into the Central Gulf of Alaska Saturday evening (9/25) with 35 kt northwest winds forecast at 41N 165W.  It is to track rapidly east on Sunday with up to 45 kt northwest winds forecast at 37N 152W taking aim on Hawaii and the US West Coast with seas at 23 ft at 37N 160W,  then lifting slightly northeast in the evening with 40 kt northwest winds at 38N 145W and 24 ft seas at 37N 150W focusing entirely on the California and Baja. It's to hold near there on Monday while slowly dissipating with seas in the 24 ft range at 38N 142W.   If this occurs a nice pulse of 13-14 sec period north swell could push into Hawaii with very west angled swell into California.  Of course this is only a dream by the models at this early date.

MJO/ENSO Update (reference):   As of Tuesday (9/21) the Southern Oscillation Index (SOI) continued solid in the positive range. The daily SOI was at 18.54 and has been that way in excess of 64 days now. The 30 day average was at 23.65 9actually down a nudge) with the 90 day average up to 19.18.  The Inactive Phase of the MJO appears to still be in control.  

Wind anomalies as of Monday (9/20) at the 850 mb level (approx 5000 ft up) as defined by models indicated an almost neutral (normal) wind pattern in control with only weak west anomalies pushing into Central America and weak east anomalies over the Philippines and expected to fade by the weekend (9/25). After that a dead neutral pattern is expected to take hold through 10/10 with no sign of the supposed development of the Active Phase of the MJO previously forecast. A weak incarnation of the  Active Phase of the MJO was forecast build over the width of the Indian Ocean pushing into the West Pacific on 9/25, barely making it halfway to the dateline then stalling and dissipating there into 10/5. But that appears to not be the case now.

We believe the remnants of El Nino are just about gone from the upper atmosphere. The expectation is that we'll see a building moderate to moderate.cgius strength La Nina Pattern (where the Inactive Phase takes control) for the remained of 2010 extending well into 2011 and likely to early 2012. In short, the next year and half is going to be tough for surfers on west facing shores in the Eastern Pacific and Eastern Atlantic, though east facing shores of the West Pacific and Atlantic might do well from the Inactive Phase's dominance.     

Sea Surface Temp anomaly data (9/13) indicates that downright colder than normal waters continue to expand their grip on the equator covering solidly from South America west to the dateline and beyond and are in fact getting cooler and covering a larger area over time, extending the whole way to New Guinea.  The coldest waters extended from a point south of Hawaii to just west of the dateline, a clear signal of strong easterly winds there and solid upwelling. Feeder bands of cooler than normal water continued building off the US West Coast and South America sweeping fully to the dateline, only serving to reinforce what is already an impressive La Nina pattern, suggesting stronger than normal high pressure has built in both hemispheres and upwelling is in full effect in the Gulf of Alaska and off South America. This is good for sea life and the food chain (since they tend to like colder waters), but bad for storm production. Looks like a classic La Nina setup. This continues the turn for the worse and only seems to be getting stronger. At the same time a massive buildup of warmer than normal waters has stalled in the Atlantic almost bleeding into the far Eastern Pacific. This was of concern to hurricane forecasters there. But it appears residual upper level shear from El Nino has done a good job of if not chopping the tops off developing systems, at least directing then to the north. But that shear appears to be fading some as we move into the heart of hurricane season in the Atlantic. Regardless of this year, next year might be a very strong hurricane producer, with the El Nino shear gone and a mature La Nina in control.

Below the surface on the equator no Kevin Wave activity was present and if anything colder than normal water was building strong over the dateline and pushing east (sort of like a cold Kelvin Wave). This pocket was -6 degs below normal (getting colder). Not good. 

Over the entire Equatorial Pacific trades were blowing all the way to the Philippines and beyond. And now from a historical perspective these easterly winds were anomalous, blowing harder than normal from the east to the west, as would be expected looking at all the other data. But this is a rather recent development, with only normal winds indicated prior to 9/11. The interesting twist to all this is that the Pacific current that runs along the equator turned abruptly from flowing towards South America to flowing towards the Philippines in mid-March (2010), right as the SOI started it's impressive drive into positive territory and the North Pacific winter storm machine abruptly shut down. And it has not wavered since. But trades never waiver from the normal range.  This suggests trade wind anomalies might be a byproduct of the Pacific equatorial current change and not the other way around i.e. the trades do not drive the temperature change initially, but the current change does. And then the atmosphere responds in kind to the change, building high pressure and reinforcing the flow and water temps. Said a different way, the change in the current might actually foretell a coming change in the trades, and then with the advent of the trade wind change, it only serves to reinforce the current in a self a.cgiifying loop, until such time as the cycle runs it's course and the self feeding system collapses over a multiyear period. At that time the current then switches direction, and a whole new self-enforcing cycle stars anew. Something to consider (regarding the formation and El Nino/La Nina).     

El Nino is effectively gone and slowly losing it's grip on the global upper atmospheric weather pattern. Still some lingering impact might continue through early Fall 2010, but likely not enhancing the storm track in the South Pacific any longer. A transition to cooler than normal conditions (La Nina) is expected through Nov 2010, and the signs continue to point to a La Nina pattern for the long term future.   

See more details in the   El Nino update.


South Pacific

Beyond 72 hours high pressure is to take control over the Southwest Pacific at 1032 mbs pushing down to and over the Ross Ice Shelf.  No swell producing fetch is forecast. Weak low pressure is forecast building over the Southeast Pacific but winds to remain below 35 kts. In short, nothing of interest is indicated.  

Details to follow...


External Reference Material: El Nino Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), Kelvin Wave

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Local Interest

Interview with Stormsurf: Coastviews Magazine has written up a very nice article on Stormsurf in their latest edition. You can read it here:

Stormsurf Hi-Res Coastal Precipitation Models Upgraded Though a bit late in the season, on 3/20 we i.cgiemented the same basic technology used in our new snow/ski models into the coastal hi-res precipitation models. So now you can not only determined whether rain is forecast for your area, but also snow. And not just light, medium or heavy snow like most sites, but the exact snowfall amount (in inches) for each 3 hr frame of the animation. Here's a sa.cgie, but now this approach is used in all our precipitation models.

Stormsurf Precip Models Upgraded! On 2/20 we upgraded some of the broader precipitation models driven by the hi-def GFS model to include snow fall. The algorithm used is similar to the recently released snow models for the Southwest US in that the areas where snow is expected are identified and the exact amount of snow forecast over a 3 hr window is e.cgiicitly color coded. For East and West Coast US interests the following links provide good exa.cgies:
West Coast:
East Coast:

Stormsurf Weather Models have all been upgraded! Over the New Years break we installed all new and upgraded weather models. Also new are experimental snow models for the Southwest US. Take a look here:

Read about Eric Nelson and Curt Myers, the makers of Ride-On and other Big Wave Surf Movies here:

Ride On! Powerlines new big wave epic is now available on DVD. Get the entire big wave story of the 2008-2009 season here:

Click here to learn more about Casa Noble Tequila! Casa Noble Tequila If you are looking for an exquisite experience in fine tequila tasting, one we highly recommend, try Case Noble. Consistently rated the best tequila when compared to any other. Available at BevMo (in California). Read more here:

Interview With Stormsurf:  The crew at worked with Stormsurf on a feature about why surfers should be able to read wave charts themselves. They are firm believers that a little learning can go a long way to help your surfing.  This is a great article to help convince your friends that they can benefit from being able to read the data themsleves rather than just relying on the forecasts of others.  See the full thing here:  Create Your Own Surf Forecast with Stormsurf

Wave Model Upgrade Status Report: At this point we believe the installation of the new wave models is complete, with no problems being reported, the server stabilizing and the much requested return of the old style hemispheric Surf Height models now operational (again) and running side-by-side along the new ones. We thank you for your patience and input as we went though this process.  Your feedback helps guide our efforts and ultimately results in a better product for everyone.  Now we're off to start providing better menus to some wave model products most of you probably haven't uncovered yet (site specific graph and text forecasts), updateing the wave model FAQs and then upgrading the Weather Models.  

New Wave Model Facts: Click HERE to read more about the new wave models. Important info.

Story About Stormsurf: The folks at SurfPulse (and specifically author Mike Wallace) have written up a really nice article about Stormsurf, complete with some good pics. Learn about how we came to be and a little of where we are going. Check it out here:

Stormsurf Video: Just for fun - here's a clip about Stormsurf that ran on Bay Area TV a while back. Thought you might enjoy it:

Time Zone Converter By popular demand we've built and easy to use time convert that transposes GMT time to whatever time zone you are located. It's ion left hand column on every page on the site near the link to the swell calculator.

Need Chiropractic Help? Visit our friends at Darrow Chiropractic. Not only will Dr. Darrow fix you up, he might give you some big wave surfing tips too! See more here:

Stormsurf Google Gadget - Want Stormsurf content on your Google Homepage? It's si.cgie and free. If you have Google set as your default Internet E.cgiorer Homepage, just click the link below and a buoy forecast will be added to your Google homepage. Defaults to Half Moon Bay CA. If you want to select a different location, just click on the word 'edit', and a list of alternate available locations appears. Pick the one of your choice. Content updates 4 times daily. A great way to see what waves are coming your way! .xml

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Surf Height-Swell Height Correlation Table


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