344
FXUS66 KSGX 101553
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
853 AM PDT WED SEP 10 2025
SYNOPSIS
A LOW PRESSURE SYSTEM MOVING SLOWLY INTO THE WESTERN STATES
CONTINUES TO SPREAD COOLING INLAND WITH HIGH TEMPERATURES FOR
INLAND AREAS 10 TO 15 DEGREES BELOW AVERAGE TODAY AND THURSDAY.
THERE WILL BE INLAND WARMING OF AROUND 5 DEGREES FOR FRIDAY AND
SATURDAY WITH NOT MUCH CHANGE FOR SUNDAY, WITH FURTHER WARMING
INTO WEDNESDAY. MONSOONAL MOISTURE MAY MAKE A RETURN DURING THE
MIDDLE AND LATTER PART OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE
A DEEPER, PATCHY MARINE LAYER SUFFICIENTLY PUSHED INLAND OVERNIGHT,
COVERING ALL OF THE COASTAL BASIN AND INLAND REGIONS. ONLY A FEW
SITES REPORTED LIGHT DRIZZLE THIS MORNING, WITH MOST LOCATIONS
REMAINING DRY, LIKELY TO BE THE SAME STORY FOR THURSDAY MORNING.
GUSTY WINDS HAVE GENERALLY WEAKENED, WITH ONLY THE BANNING PASS
STILL SEEING GUSTS ABOVE 40 MPH. COOLER WEATHER PREVAILS TODAY AND
TOMORROW AS AN UPPER LEVEL LOW PUSHES DOWN INTO SOUTHERN
CALIFORNIA. NO SIGNIFICANT CHANGES FROM THE PREVIOUS FORECAST
PACKAGE WITH A SLOW WARM UP EXPECTED FOR THE WEEKEND, WITH MORE
SUBSTANTIAL WARMING INTO EARLY NEXT WEEK. WHILE WE CONTINUE TO
TALK ABOUT MONSOONAL MOISTURE MOVING IN EARLY NEXT WEEK, LACK OF
ALIGNMENT IN THE GLOBAL MODELS KEEPS CONFIDENCE IN THIS OCCURRING
BELOW 25% FOR NOW.
PREVIOUS FORECAST
SHORT TERM (TODAY THROUGH FRIDAY)
A LOW PRESSURE SYSTEM MOVING SLOWLY INLAND INTO THE WESTERN STATES
WILL BRING ADDITIONAL COOLING FOR THE MOUNTAINS, DESERTS, AND
INLAND VALLEYS OF 4 TO 8 DEGREES FOR TODAY WITH NOT MUCH CHANGE
FOR THURSDAY. HIGH TEMPERATURES FOR TODAY AND THURSDAY WILL BE 10
TO 15 DEGREES BELOW AVERAGE FOR THE MOUNTAINS, HIGH DESERT, AND
INLAND VALLEYS AND AS MUCH AS 15 TO 20 DEGREES BELOW AVERAGE FOR
THE HIGHER ELEVATIONS OF THE MOUNTAINS. HIGH TEMPERATURES FOR
TODAY AND THURSDAY WILL RANGE FROM THE LOWER 70S NEAR THE COAST TO
THE MID 70S TO LOWER 80S FOR THE INLAND VALLEYS WITH THE LOWER TO
MID 90S FOR THE LOWER DESERTS. HIGH TEMPERATURES ON FRIDAY WILL BE
A DEGREE OR TWO WARMER.
THE MARINE LAYER WILL DEEPEN TO AROUND 3000 FEET FOR TODAY AND
THURSDAY WITH NIGHT AND MORNING COASTAL LOW CLOUDS COVERING MUCH
OF THE COAST AND VALLEYS. THE MARINE LAYER WILL BEGIN TO DECREASE
IN DEPTH FOR THURSDAY NIGHT AND FRIDAY WITH COASTAL LOW CLOUDS
EXTENDING INLAND INTO PORTIONS OF THE INLAND VALLEYS.
GUSTY SOUTHWEST TO WEST WINDS FOR THE MOUNTAINS AND DESERTS
DURING THE AFTERNOON AND EVENING WILL GRADUALLY DIMINISH EACH DAY
FOR TODAY THROUGH FRIDAY WITH GUSTS TO 30 TO 40 MPH FOR THIS
AFTERNOON AND EVENING WITH GUSTS IN THE NORTHERN COACHELLA VALLEY
BELOW THE SAN GORGONIO PASS TO 40 TO 50 MPH.
LONG TERM (SATURDAY THROUGH TUESDAY)
HIGH TEMPERATURES ON SATURDAY WILL WARM FROM A FEW DEGREES AT
LOWER ELEVATIONS TO AROUND 5 DEGREES FOR THE MOUNTAINS WITH NOT
MUCH CHANGE ON SUNDAY. HIGH TEMPERATURES FOR THE WEEKEND WILL BE
AROUND 4 TO 8 DEGREES BELOW AVERAGE FOR THE MOUNTAINS, DESERTS,
AND INLAND VALLEYS WITH HIGH TEMPERATURES RANGING FROM THE LOWER
70S NEAR THE COAST TO THE 80S FOR THE INLAND EMPIRE AND MID TO
UPPER 90S FOR THE LOWER DESERTS. THE MARINE LAYER WILL BECOME A
LITTLE SHALLOWER WITH NIGHT AND MORNING COASTAL LOW CLOUDS
SPREADING INTO THE WESTERN VALLEYS LATE EACH NIGHT.
FOR MONDAY THROUGH WEDNESDAY, LOW PRESSURE WILL BEGIN TO WEAKEN
ACROSS CALIFORNIA, BUT WITH INCREASING MODEL SPREAD ON THE
AMOUNT OF WEAKENING AND THE RESULTING AMOUNT OF WARMING. NBM HAS
WARMING OF 5 TO 10 DEGREES FOR INLAND AREAS FOR MONDAY THROUGH
WEDNESDAY WITH WEDNESDAY HIGH TEMPERATURES AROUND AVERAGE FOR THE
DESERTS AND A FEW TO AROUND 5 DEGREES ABOVE AVERAGE FOR THE COAST
AND VALLEYS WITH HIGH TEMPERATURES RANGING FROM THE 70S NEAR THE
COAST TO THE 90S FOR THE INLAND EMPIRE WITH THE UPPER 90S TO 102
FOR THE LOWER DESERTS.
SOME MONSOONAL MOISTURE MAY BEGIN TO RETURN FOR THE MIDDLE AND
LATTER PART OF NEXT WEEK WITH NBM DAILY CHANCES FOR MEASURABLE
RAINFALL FOR BIG BEAR INCREASING TO 7 PERCENT ON WEDNESDAY, 11
PERCENT ON THURSDAY, AND 16 PERCENT ON FRIDAY.
AVIATION
101530Z...COAST/VALLEYS...SKY CONDITIONS BEGIN TO SCATTER OUT OF
INLAND AREAS THROUGH 17Z, THEN COASTAL AREAS 17-20Z, BUT ONLY
PARTIAL OR INTERMITTENT CLEARING AT THE IMMEDIATE COAST. LOW CLOUDS
BASED 1800-2200 FEET MSL AND TOPS TO 2500 FEET WILL REDEVELOP MOVE
INLAND AFTER 00Z, EVENTUALLY TO FILL THE COASTAL BASIN BY 3Z-12Z
THURSDAY.
MOUNTAINS/DESERTS...PREVAILING VFR CONDITIONS TODAY AND TONIGHT.
STRONG WINDS OF 25-30KT WITH GUSTS UP TO 40KT 19Z TODAY-08Z THURSDAY
THROUGH MOUNTAIN PASSES INTO ADJACENT DESERTS, CAUSING LLWS AND
UP/DOWNDRAFTS IN POCKETS IN LEE OF MOUNTAINS.
MARINE
OCCASIONAL NORTHWEST WIND GUSTS EXCEEDING 20 KT IN VICINITY OF SAN
CLEMENTE ISLAND TODAY AND THURSDAY AFTERNOON AND EVENING. OTHERWISE,
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...ZUBER
AVIATION/MARINE...VILLAFANE
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