730
FXUS66 KLOX 310349
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
849 PM PDT Sat Aug 30 2025

.SYNOPSIS...30/833 PM.

Very warm conditions will continue through most of the coming
week, generally peaking Sunday through Tuesday, including Labor
Day. There is a high risk of heat related illnesses in sensitive
populations. Monsoonal moisture will arrive again on Tuesday and
keep a low but present risk of showers and thunderstorms through
the remainder of the week.

&&

.SHORT TERM (SAT-TUE)...30/847 PM.

***UPDATE***

Temperatures were warmer than forecast from the Santa Barbara
south coast to the Ventura coastal plains, where highs peaked at
89 for Santa Barbara City and 86 at the local office. Given
afternoon onshore flow looks similar to today along with the
building heat, temperatures were increased in these areas for
Sunday and Monday. Adjustments may also be needed Tuesday, around
the expected peak of the heat. Will need to consider heat
advisories for both the Ventura coastal plains and the immediate
coast Monday and Tuesday. Otherwise, current forecast looks on
track.

***From Previous Discussion***

Another extended heat wave underway today through the middle of
next week. Some interior locations have already topped 100
degrees today and triple digit temperatures will become more
widespread over the next few days. In short term, northeast winds
gusted between 15 and 30 mph today across the wind prone hills
and canyons of San Luis Obispo and Santa Barbara Counties due to a
2 millibar offshore trend in the pressure gradients. Several
projections show even stronger and more widespread northeast winds
overnight and Sunday across the wind prone hills and canyons of
San Luis Obispo and Santa Barbara counties, with gusts mostly in
the 20 to 35 mph range. This offshore wind push has brought
substantial warming and drying across interior and wind prone
foothills/canyons of San Luis Obispo/Santa Barbara Counties today,
becoming more pronounced and widespread on Sunday with
temperatures climbing into the 90s to lower 100`s. Heat advisories
go into effect across a large portion of San Luis Obispo and
Santa Barbara counties on Sunday, Even more populated areas such
as San Luis Obispo, Arroyo Grande, and Nipomo will have a high
probability of climbing into the 90s on Sunday. The combination of
hot temperatures, low humidities, and offshore winds will bring
unusually elevated fire weather concerns across the Central Coast
foothills/canyons this weekend, especially late tonight into
Sunday.

A large ridge of high pressure blanketing the western states,
will expand and strengthen over the next 12 to 24 hours and change
very little through at least Monday. As a result, the rest of the
region is also on track for very warm conditions that will last
for several days, with Monday through Wednesday likely the
hottest outside of the Central Coast. Calendar day records are
really high for this coming week, so not anticipating any records.
While temperatures will only be around 10 degrees above normal,
that is very warm considering this is climatologically our hottest
time of the year, and considering the plethora of outdoor
activities associated with the Labor Day holiday, the risk for
heat illness is abnormally high - especially for those that are
most susceptible (like the old, young, hikers, and those without
air conditioning). While the heat advisory for the Central Coast
is only in effect for Sunday, the other heat advisory headline
areas for the valleys, mountains, and inland LA county coast
(including downtown Los Angeles) are in effect from Sunday through
Tuesday. As we draw closer to the event, other coastal areas
(especially LA county immediate coast) may need to be included in
a Heat advisory by Monday or Tuesday. Some model guidance showing
weakest onshore gradients on Tuesday, likely leading to the
warmest coastal temperatures. During the peak of the heat on
Monday and Tuesday, high temperatures between 95 and 106 degrees
will be common, with highs in the 86-96 degree range for the
inland coastal plain. In addition, already seeing warm overnight
lows in the 70s across foothill/mountain areas, and that trend
will likely increase the next few nights, adding to the heat
risk. By Tuesday morning, we will likely see minimum temperatures
above 70 across much of the LA metro area.

Monsoonal moisture will likely return to the region starting
Monday night or Tuesday with about an 80 percent chance of PWATs
above one inch across eastern Los Angeles County. For Monday
night, there is a 10 percent chance of light showers for areas
south of Point Conception. By Tuesday afternoon, there is a 15-30
percent chance of monsoonal thunderstorms for the San Gabriel
mountains and Antelope Valley, with a 5-15 percent chance for
other areas south of Point Conception. This leading edge of the
monsoon surge may be somewhat drier at low levels, which may lead
to the potential for isolated dry lightning strikes and
gusty/erratic downburst/outflow winds. The hotter temperatures
and increased instability will also lead to widespread elevated
fire weather concerns for the interior, with an increased risk
for large plume dominated fires (especially in the mountains and
foothills). Please see additional fire weather details in the
Fire Weather Planning Forecast discussion (LAXFWFLOX).

With onshore flow expected to be quite weak the next few days,
looking for any low clouds and fog to mostly be confined to
immediate portions of the Central Coast, as well as LA/Ventura
counties Coast. Patchy dense fog certainly a possibility as the
inversion will continue to lower and strengthen.

.LONG TERM (WED-SAT)...30/238 PM.

Weak ridging will likely persist on Wednesday and Thursday.
Wednesday will likely be another hot day, with heat advisories
potentially extending for parts of our forecast area. By Thursday
and Friday, some cooling is expected, as heights drop and onshore
flow increases. With the increased monsoon moisture and overall
hot air mass in place, Tuesday night may end up being the warmest
night, with much of the LA metro area remaning above 70 degrees.
In addition, many foothill and mountain areas may have lows in the
mid 70s to lower 80s, adding to the heat risk.

We will likely continue to be on the western edge of the monsoon
surge from Tuesday night through Friday. The best chances of
thunderstorms (15-30%) will likely persist across the San Gabriels
and Antelope Valley, but with some upper level east-southeast flow
and some potential embedded vorticity disturbances, there is a
smaller chance (5-15%) for showers/thunderstorms across other
portions of the forecast area south of Point Conception, including
coastal and valley areas. And also can`t rule out some nocturnal
shower/ thunderstorm activity at some point during the extended
period.

&&

.AVIATION...31/0249Z.

At 2309Z at KLAX, there was no marine layer. There was a surface
based inversion with a top at 2700 ft with a temperature of 27 C.

Low confidence in TAFs for KOXR, KCMA, KSMO, KLAX, and KLGB due
to uncertainty of development of low clouds tonight. There is a
40% chance for no low clouds tonight at any aforementioned site.
If clouds arrive, arrival time may be off +/- 3 hours and minimum
cig heights may be off +/- 300 feet. There is a 10-30% chance for
vsbys less than 1SM, highest at KOXR and KCMA.

High confidence in remaining TAFs. There is a 20% chance for NE
winds gusting to 20 kts at KSBP between 08Z and 17Z.

KLAX...Low confidence in TAF after 08Z, high confidence until
then. 40% chance no low clouds develop, but if they do, there is a
15% chance for vsbys 1/2SM-1SM at times due to shallow marine
layer. Arrival may be off +/- 3 hours and minimum cig height may
be off 300 feet. Clearing time may be off +/- 90 minutes.

KBUR...High confidence in TAF.

&&

.MARINE...30/839 PM.

High confidence in 20-30 kt NW winds in the Outer Waters from
Point Sal north to Point Piedras Blancas continuing through Labor
Day (Monday), with moderate confidence in Gale Force gusts of
34-38 kts tonight and Sunday night. Moderate confidence in the
remaining Outer Waters remaining below Small Craft Advisory (SCA)
criteria through Sunday morning. Winds may increase to marginal
SCA thresholds Sunday afternoon thru evening, but chances increase
Monday. From Tuesday into Thursday, the best chances for SCA
winds are focused around Point Conception south to San Nicolas
Island. A relative lull in winds will be likely each morning.

Moderate confidence in SCA conditions for the nearshore waters
along the central coast in the afternoon and evenings Sunday and
Monday, then lighter winds and smaller seas likely.

Aside from fairly seasonal afternoon and evening localized NW
wind gusts 20-25 kts in the far Western Portion of the Santa
Barbara Channel and 15-20 kts in the San Pedro Channel, light
winds and small seas will be common for the nearshore waters south
of Point Conception through Labor Day. Better chances for more
widespread SCA winds on Tuesday & Wednesday in the afternoon and
evenings.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect from 10 AM Sunday to 6 PM PDT
      Tuesday for zones 38-344-345-353. (See LAXNPWLOX).
     Heat Advisory remains in effect from 10 AM Monday to 6 PM PDT
      Tuesday for zones 88-356>358-368>376-378-379-548. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Monday evening for
      zones 340-346-354-362-366. (See LAXCFWLOX).
     Heat Advisory remains in effect from 10 AM to 6 PM PDT Sunday
      for zones 341>343-347>349-351. (See LAXNPWLOX).
PZ...Gale Warning in effect until 3 AM PDT Sunday for zone 670. (See LAXMWWLOX).

&&

$$

PUBLIC...Phillips/Gomberg
AVIATION...Phillips/Lewis
MARINE...Lewis/Ciliberti
SYNOPSIS...RK/CC

weather.gov/losangeles

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