265
FXUS66 KLOX 300947
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
247 AM PDT Wed Sep 30 2026

.SYNOPSIS...30/221 AM.

Little change in weather conditions is expected through Thursday
with temperatures 3-6 degrees above normal. Areas of morning low
clouds and fog are possible near the coast as well. A major and
long lasting heat wave will begin Friday and last through all of
next week at least with with dangerously hot temperatures.

&&

.SHORT TERM (TDY-FRI)...30/1206 AM.

...A VERY DANGEROUS AND LONG LASTING HEAT WAVE NEXT WEEK AND
LIKELY EXTENDING INTO THE SECOND WEEK IN OCTOBER...

High pressure aloft will move into the state from the west and
remain overhead through the short term period and beyond. Hgts
will reach 588 dam today and then rise to 590 dam for Fri and Sat.

A weak eddy will bring some clouds to LA County this morning and
westerly onshore flow will bring low clouds and dense fog to the
Central Coast. There is a small chc that the low clouds will not
reach the LA cst. Much weaker offshore flow this morning and much
stronger onshore flow in the afternoon will bring 2 to 4 degrees
of cooling to the csts and vlys with the exception of the SBA
south coast and some beaches in SLO county where the return to
onshore flow will bring 5 to 10 degrees of cooling. The mtns and
far interior will see 3 to 6 degrees of warming due to the hgts
rises.

Marine layer clouds will be more extensive Thursday morning as the
eddy continues to spin. Offshore flow in the morning should clear
these clouds away by mid morning. There is, however, always a risk
that the eddy will be stronger than fcst with low clouds remaining
longer and high temps cooling. The most likely temperature
scenario calls for an additional 2 to 4 degrees of warming in most
places. Two exceptions will be the Central Coast where max temps
will hardly change at all and the San Gabriel and San Fernando
Vlys where 4 to 6 degrees of warming is likely. Max temps will end
up mostly in the 80s across the csts and 90s in the vlys. These
max temps are all about 8 degrees over normal.

The heat wave really accelerates on Friday with the 590 dam hgts,
upper level subsidence, offshore morning flow and only weak
onshore flow in the morning. The eddy will be much weaker and
there will be much less morning low clouds. Most max temps across
the csts and vlys will bump up another 3 to 5 degrees. This will
bring triple digit heat the warmest vlys and lower 90s to the
interior coastal sections. Even the beaches will have highs in the
lower 80s. There is a 30 percent chc that the offshore flow will
be a little stronger with max temps ending up 3 degrees higher
than fcst. It is very likely heat advisories will be issued for
most of the LA/VTA county cst/vlys.

.LONG TERM (SAT-TUE)...30/220 AM.

The long term forecast is all about the heat. It continues to look
like a 10 to 14 day heat wave is in store for Srn CA. High
pressure aloft will likely remain in place (with a few small day
to day changes). More importantly an extended period of offshore
flow seems more than likely as well.

Currently Saturday is forecast to be the warmest day with coastal
highs in the 90s (20 percent chc of isolated 100 to 102 degrees
readings) and vlys reaching 100 to 106 degrees. Slight cooling is
forecast Sunday with little change on Mon and Tue, but if the
offshore push is stronger than forecast this cooling could turn
out to be a mirage. These max temps are 10 to 15 degrees above
normal. The offshore flow will keep overnight lows above normal
as well which will give residents without air conditioning little
room for recovery.

All long range mdls both traditional and AI-enabled show this heat
wave reaching all the way to at least the 13th of October.

Extreme Heat Warnings are likely starting Saturday for portions of
the LA/VTA County csts and vly. Heat advisories are also likely
for any portion of the LA/VTA county csts/vlys as well as the SBA
south coast and Catalina Island. Heat Advisories may be need for
the Central Coast depending on how much offshore flow develops
there. If this heat wave is as relentless as it is currently
forecast areas with advisories may need an upgrade to warnings
due to the toll taken by day after day of heat.

One positive note - since this is more of an offshore driven event
the humidities will be lower than the earlier heat events.

&&

.AVIATION...30/0946Z.

At 0832Z at KLAX, the marine layer was 900 ft deep. The top of
the inversion was at 2000 ft with a temps of 26 C.

High confidence in VFR TAFs for KPRB, KWJF, and KPMD.

There is a 10% chance for brief IFR cigs at KSBA 13Z-17Z.

There is a 20 percent chc that vis will remain above 1/2SM at
KSBP/KSMX.

There is a 20 percent chc of IFR cigs at KOXR and KCMA 12Z-16Z.

KLAX...Moderate confidence in TAF. There is a 40 percent chc of
OVC008 conds through 17Z. There is a 30% chance of an of a 10 kt
east wind component 10Z-16Z.

KBUR...Fair confidence in TAF. There is a 15% chance of BKN008
conds 12Z-16Z.

&&

.MARINE...30/245 AM.

Small Craft Advisory (SCA) winds and steep seas affecting all the
inner waters (including the nearshore waters along Los Angeles and
Orange Counties) should drop off late tongiht, and will drop for
the outer waters late tonight.

Southerly swell from Polo (SSE) is decreasing fairly rapidly.
These swells will create larger waves and surf nearshore, which
could impact some south exposed harbor entrances.

Conditions are likely to improve to below SCA levels today into
next weekend, except for occasional northwest SCA winds near Point
Conception in the afternoon/evening hours.

&&

.BEACHES...30/245 AM.

The surf from Hurricane Polo has peaked and will lower rather
quickly through today, but strong rip currents may linger. The
high tide came in 1.0 to 1.2 feet above prediction on Tuesday and
above 7.0 feet MLLW. While the high tide will be lower on
today compared Tuesday, it will lower only a little and will
likely still be above 7.0 feet for morning high tide. With all
that in mind, the Coastal Flood Advisory and High Surf Advisory
have been replaced them with a lower-tier Beach Hazards Statement
to cover through 5 PM today for the rip current and tidal
overflow potential.

While we will get a break from the coastal flooding concerns for
the rest of the week, another hurricane swell (from soon-to-be
Hurricane Rachel) will likely bring a larger-than-Polo south
swell to southern California for the early to middle part of next
week. Thankfully tides at that time will not be extreme, but they
should be around 6.5 feet which is high enough to cause some
concern, but it all depends on how big the surf ends up.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through this afternoon for
      zones 87-349-350-354-362-366. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT early this
      morning for zones 645-650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT this morning
      for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Lewis/RK/RS
BEACHES...RK
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox