Castaic, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

130
FXUS66 KLOX 041838
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1138 AM PDT Mon May 4 2026

.SYNOPSIS...03/851 PM.

Cloudy and cool conditions will continue through Tuesday, with
increasing chances of mostly light rain. Warming and drying to
follow Wednesday through the next weekend, with high temperatures
approaching 90 degrees in some areas by Friday.

&&

.SHORT TERM (TDY-WED)...04/1225 AM.

The marine layer is over 6000 ft deep and has produced a fairly
high based (4000-6000ft) cloud deck of much of the area.
Conditions are a little clearer over the Central Coast where the
effects of the approaching upper low are mixing the atmosphere
some.

Today`s weather will come courtesy of a 560 dam upper low
currently just to the SW of Monterey Bay. The upper low will move
very slowly to the SE and will over SLO county later this
afternoon. This is a fairly dry and non dynamic system, but it
still will bring a 20-30 percent chc of rain to the area. The best
chc of rain today will be south of Pt Conception where the flow
will have the longest over water trajectory and the most PVA.
There will also be a chc of showers over the mtns where there will
be decent instability. SLO and SBA county will have a very slim
but non zero chc of a TSTM as the core of the low moves overhead
during peak afternoon heating. Rainfall amounts will mostly be
under a tenth of an inch with plenty of locations not seeing any
rain or just a trace but a few areas could see a quarter inch
under a heavier shower. Rainfall rates should also not be a
concern with the exception of any area affected by that 5 percent
chc of a TSTM. Max temps will resemble January more than May with
highs only in the 60s across the csts/vlys or 10 to 15 degrees blo
normals away from the near shore areas.

Over night the low will spin over VTA county and the best chc of
rain will shift to the mtns esp the north slopes.

On Tuesday the low is fcst to accelerate to the east and should be
over the state line by mid afternoon. A 20 to 30 percent chc of
showers will continue across the mtns of VTA and LA counties
through the day. Elsewhere look for a decrease in clouds with the
resulting increase in sunshine bringing a few degrees of warming
to the area esp to SLO and SBA counties.

On Wednesday dry NNE flow will set up over the state as a ridge
pushes into Bay Area. Hgts will rise quickly to 578 dam. There
will be a little offshore push from the north in the morning while
the onshore flow to the east will increase from weak to moderate
by afternoon. Skies will be sunny. Coastal temps will warm 3 to 5
degrees tempered by the onshore flow. Away from the coasts,
however, the sunshine and hgt rises will combine to bring a very
noticeable 5 to 10 degree warm up with 10 to 15 degrees across
mtns and far interior.

.LONG TERM (THU-SUN)...04/228 AM.

All signs pointing to an xtnd warm up for the long term. All mdls
agree that the east Pac ridge will nose into the state from the
west. Hgts will rise to 582 dam on Thu and stay there through Sat
and then bump up a little to 584 dam on Sunday. The biggest
question mark for the forecast will be the E/W sfc gradients.
While there is decent agreement that there will be weak offshore
flow from the north, there is considerable disagreement on what
the E/W grads will do. About half the EC ensemble grads (which
usually verify better than the GFS ensembles) are onshore in the
mornings while the other half is offshore. The deterministic EC
follow the mean pretty closely with its grads just a little
onshore. For now will go with that, but have to keep an eye on
this critical parameter because if it does go offshore the already
warm temps will soar even higher.

Right now most areas are looking at 3 to 6 degrees of warming
Thursday, 1 to 3 degrees Friday, 2 to 4 Saturday and 1 to 2
degrees on Sunday. Cst/Vly temps start out 2 to 4 degrees above
normal on Thursday and rise to 5 to 10 locally 12 degrees on
Sunday. The mtns and far interior will end up 15 to 18 degrees
over normal on Sunday. On Sunday max temps across the near shore
areas will be in the lower to mid 70s, the rest of the csts in
the upper 70s and to mid 80s. The vlys will be mostly in the lower
90s. If the offshore flow from the east does develop these temps
could be 4 to 8 degrees highers with some locations possibly
hitting 100 degrees.

&&

.AVIATION...04/1838Z.

At 1817Z at KLAX, there was a deep moist layer up to 7000 ft.

Moderate confidence in TAFs. Wind speeds/gusts may be off by 5 kt
at times during peak winds at all sites. There is a 20-30 percent
chc -SHRA along with a 5 percent chc of a -TSRA from 22Z-04Z.
Brief MVFR cigs will be possible at anytime through the period.

KLAX...Moderate confidence in TAF. There is a 20-30 percent
chance of -SHRA 22Z-04Z. High confidence that any east wind
component with be AOB 6kts.

KBUR...Moderate confidence in TAF. There is a 10-20 percent
chance of -SHRA 22Z-04Z.

&&

.MARINE...04/837 AM.

For the nearshore waters inside the SoCal Bight, Small Craft
Advisory (SCA) west winds are likely (40-60% chance) Tuesday
afternoon and evening with a chance (30-40% chance) Wednesday and
Thursday nights, mainly in the channel.

Nearshore along the Central Coast there is a 30% chance for SCA NW
winds Tuesday and Wednesday nights, with a 30 to 40% chance of SCA
conds Thursday afternoon and night.

For the outer waters, SCA NW winds are likely (40-60% chance)
on Tuesday for the waters near Point Conception to the northern
Channel Islands, possibly extending south to San Nicolas island.
Winds will increase again from the NW Wednesday night (for PZZ676)
into Thursday for the remaining outer zones through Thursday
night. Stronger winds will be possible Friday into the weekend.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 9 PM PDT this evening for zones
      381-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Rorke
AVIATION...Schoenfeld
MARINE...Ciliberti/RS
SYNOPSIS...RK

weather.gov/losangeles

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