Swell Matrix

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard Ca

828 pm PDT Tue Sep 22 2026

Synopsis

22/320 PM.

High temperatures will peak on Wednesday, with highs 5 to 10 degrees above normal. The marine layer will shrink during this time, with overnight low clouds and fog limited to coastal areas through at least Thursday night.

Short Term

(Tue-Fri), 22/806 PM.

***UPDATE***

Southwest California was treated to another fairly quiet day in what has been a long stretch of benign weather. However, today is the last day of below normal temperatures for the rest of the work week. Temperatures will increase 6-12 degrees across most of the region areas thanks to the combination of a pop up ridge nosing in, light offshore flow (with a pronounced offshore trend), and limited low cloud coverage. Still expecting tomorrow the be the warmest day as we will see winds trend back onshore and likely be weakly onshore through the weekend. Offshore flow is expected to generally peak in the 20-30 mph across favored mountains and foothills late tonight into Wednesday morning, thus advisories are not anticipated anywhere.

***From Previous Discussion***

Wednesday will be the warmest day of the next 7 as a little pop up ridge arrives overhead. There will be weak offshore flow from both the east and the north in the morning and only weak onshore flow in the afternoon. There will be very limited morning low clouds mostly confined to the SBA county west coast. Total sunshine, offshore flow in the morning and the ridge will all combine to warm max temps 8 to 12 degrees. This warming will bring 80s to the csts and 90s to the vlys with a moderate risk of heat exhaustion. On the plus side, a dry airmass and light winds will allow for good evening to overnight temperature recoveries, limiting heat impacts and NO need for heat products. The max temps are about 5 degrees above normal for areas south of Pt Conception but are 10 degrees above normal for the Central Coast.

Thursday weak troffing and a return to onshore flow will result in an increase morning low clouds across the csts as well as a 2 to 4 degree cool down. Max temps, still, will end up 2 to 4 degrees above normal (4 to 8 across the Central Coast).

Long Term

(Sat-Tue), 22/936 AM.

On Friday Srn CA will be sandwiched between a decent sized trof to the north just off the WA coast and a large upper high over TX. This will result in dry SW flow over the Srn CA. Hgts will be near 584 dam. This pattern will be fairly stagnant and will last through Sunday. At the sfc fairly weak onshore flow will persist except in the mornings where there will be weak offshore flow from the north. The weather will be pleasant and benign with low clouds across the some of the csts (esp the western SBA county cst), but otherwise mostly clear skies.

Most max temps will cool a little Friday and Saturday. The best cooling will be north of Pt Conception where the trof will have the greatest effect. Even with this cooling max temps will remain a few degrees over normal. Blended ensemble guidance still shows 4 to 8 degrees of cooling on Sunday, which now seems a little more reasonable as now a sharper trof with falling hgts will likely move into the state. Still the amount of cooling may be overdone esp over LA county.

Weak ridging and building offshore flow from the north builds in on Monday. There is a 50-60 percent chc of weak offshore flow from the east in the morning as well. Look for a mostly sunny day with some warming esp across the Central Coast. Breezy northerly winds are possible for prone interior areas to the Santa Ynez mountain range.

Distant tropical cyclones to the SSW may send another round of swells and large surf and dangerous rip currents to south or southwest facing coasts by late this weekend (see Beaches section below for additional information. There is also a good chance of some increasing mid to high clouds well ahead of these systems. The deepest tropical moisture will likely be shunted to our east through the period with only a 5-10 percent chance that deep enough moisture makes it far enough north for showers focused across LA to maybe Ventura Counties early next week.

Aviation

23/0157z.

At 0015Z at KLAX, the marine layer was 1600 ft deep. The top of the inversion was at 3400 feet with a temperature of 22 C.

High confidence in VFR TAFs for KPMD, KWJF, KBUR, and KVNY.

Moderate to low confidence in remaining TAFs. There is a 20% chc of LIFR CIGs 23/10Z-16Z at KPRB. There is a 30% chc of low MVFR CIGs 012 23/10Z-17Z at KSMO. 40% chc CIGs do not occur a KLGB and KLAX.

For KSBP and KSMX, timing of CIG/VSBY restrictions may be off +/- 2 hours. There is also a 30% chance CIGs do not develop at KSBP and 20% chance at KSMX.

KLAX, Good confidence in VFR conds thru 23/08Z. Fairly low confidence on if CIGs 012 (+/- 200 ft) arrive with a 30-40% that VFR conditions persist through forecast period. No significant east wind component expected.

KBUR, High confidence in TAF.

Marine

22/828 PM.

Good confidence in Small Craft Advisory (SCA) west to northwest winds continuing into early Wednesday morning across the Outer Waters. There is a 30% chance that advisories across the outer waters (PZZ670/673) will need to be extended into Wednesday afternoon/eve. SCA winds may return as early as Thursday evening across the Outer Waters with increasing chances Friday into the weekend, along with a low to moderate potential of reaching into portions of our inner waters. There is a 30% chance of local Gale Force wind gusts across the outer waters north of Point Conception late Friday afternoon and evening.

Beaches

22/814 PM.

The eastern Pacific is currently active with hurricane Polo, tropical storm Odalys, and a developing disturbance southeast of Hawaii. This activity will produce southerly swells (SW-SE) which will impact the southern California coastline as early as Friday into the weekend, with better chances early next week. Confidence is currently low on the evolution of these systems, the magnitude, and exactly how the swells will propagate. Stay tuned for future updates as we continue to monitor these storms.

Watches, Warnings, Advisories

Ca, NONE. PZ, Small Craft Advisory in effect until 11 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 9 PM PDT this evening for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Wednesday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zone 676. (See LAXMWWLOX).

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