643  
FXUS66 KSGX 081014  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
314 AM PDT WED OCT 8 2025  
   
SYNOPSIS
 
 
A LOW PRESSURE SYSTEM OFF THE WEST COAST WILL DRAW TROPICAL  
MOISTURE NORTHWARD INTO THE AREA FOR THURSDAY INTO FRIDAY NIGHT  
WITH INCREASING CHANCES FOR SHOWERS AND A CHANCE FOR THUNDERSTORMS.  
COOLER WITH DRYING FOR SATURDAY THROUGH MONDAY. FOR TUESDAY AND  
WEDNESDAY OF NEXT WEEK, A LOW PRESSURE SYSTEM MOVING TO NEAR THE  
WEST COAST WILL BRING A CHANCE OF SHOWERS.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
   
SHORT TERM (TODAY THROUGH FRIDAY)
 
 
THE MARINE INVERSION HAS SLOWLY STRENGTHENED AND DECREASED  
SLIGHTLY IN DEPTH OVER THE PAST 48 HOURS WITH COASTAL LOW CLOUDS  
NOT SPREADING AS FAR INLAND INTO THE SAN DIEGO COUNTY VALLEYS AS  
THE PAST TWO MORNINGS. NOT MUCH CHANGE IN HIGH TEMPERATURES IS  
EXPECTED FOR TODAY WITH HIGH TEMPERATURES A FEW DEGREES BELOW  
AVERAGE FOR THE COAST INTO PORTIONS OF THE VALLEYS AND A FEW  
DEGREES ABOVE AVERAGE FOR THE MOUNTAINS AND HIGH DESERT. HIGH  
TEMPERATURES FOR TODAY WILL RANGE FROM AROUND 70 NEAR THE COAST TO  
THE 80S FOR THE INLAND EMPIRE WITH THE MID TO UPPER 90S FOR THE  
LOWER DESERTS.  
 
FOR THURSDAY INTO FRIDAY NIGHT, A LARGE LOW PRESSURE SYSTEM  
CENTERED OFF THE WEST COAST WILL DRAW MOISTURE FROM THE REMNANTS  
OF WEAKENING HURRICANE PRISCILLA NORTHWARD INTO THE AREA,  
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS. THE GREATER  
CHANCES FOR HEAVIER RAINFALL ARE FROM THE MOUNTAINS OF SAN  
BERNARDINO, RIVERSIDE, AND SAN DIEGO COUNTIES EASTWARD ACROSS THE  
DESERTS INTO ARIZONA WITH DECREASING CHANCES TOWARD THE WEST.  
 
HIGHER-RESOLUTION MODEL GUIDANCE SHOWS BANDS OF SHOWERS WITH A  
SLIGHT CHANCE OF THUNDERSTORMS MOVING NORTHWESTWARD ACROSS THE  
AREA ON THURSDAY MORNING WITH ADDITIONAL CHANCES FOR SHOWERS AND  
THUNDERSTORMS DURING THE AFTERNOON MORE FOCUSED OVER THE MOUNTAINS  
EASTWARD ACROSS THE DESERTS. CHANCES FOR SHOWERS AND THUNDERSTORMS  
WILL CONTINUE AT TIMES THROUGH FRIDAY INTO FRIDAY EVENING. NBM  
CHANCES FOR ONE INCH OR MORE OF RAINFALL IS AROUND 5 PERCENT FOR  
THE MOUNTAINS. HOWEVER, THE HRRR DOES SHOW THE POTENTIAL FOR  
6-HOURLY RAINFALL TO AROUND 1.5 INCH FOR PORTIONS OF THE MOUNTAINS  
AND DESERTS FOR THURSDAY AFTERNOON.  
 
HIGH TEMPERATURES FOR THE MOUNTAINS AND DESERTS WILL BE A FEW  
DEGREES COOLER FOR THURSDAY AND AGAIN FOR FRIDAY. WITH THE  
INFLUX OF TROPICAL MOISTURE AND INCREASE IN CLOUDS, THURSDAY NIGHT  
WILL BE WARMER WITH LOW TEMPERATURES FOR EARLY FRIDAY AS MUCH AS  
15 TO 20 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS AND DESERTS OF  
SAN DIEGO COUNTY.  
 

 
   
LONG TERM (SATURDAY THROUGH TUESDAY)
 
 
THERE WILL BE DRYING AND COOLER DAYS FOR THE WEEKEND THROUGH  
MONDAY WITH HIGH TEMPERATURES ON MONDAY AS MUCH AS 12 TO 18  
DEGREES BELOW AVERAGE FOR THE HIGHER ELEVATIONS OF THE MOUNTAINS.  
HIGH TEMPERATURES ON MONDAY WILL RANGE FROM AROUND 70 NEAR THE  
COAST TO THE 70S FOR THE INLAND EMPIRE WITH THE MID 80S FOR THE  
LOWER DESERTS.  
 
FOR TUESDAY AND WEDNESDAY, ANOTHER LOW PRESSURE SYSTEM NEARING  
THE WEST COAST MAY SPREAD SHOWERS SOUTHWARD INTO SOUTHWESTERN  
CALIFORNIA. CLUSTER ANALYSIS SHOWS THE CLUSTERS WITH THE  
RELATIVELY WETTER SOLUTIONS ARE THOSE WITH THE LOW PRESSURE  
SYSTEM SLIGHTLY STRONGER AND CENTERED SLIGHTLY FARTHER TO THE  
WEST. NBM CHANCES FOR MEASURABLE RAINFALL FOR TUESDAY MORNING  
THROUGH WEDNESDAY NIGHT IS GENERALLY 20 TO 30 PERCENT FOR THE  
COAST TO THE MOUNTAINS WITH CHANCES FOR ONE INCH OR MORE OF  
RAINFALL AS MUCH AS 5 TO 10 PERCENT FOR PORTIONS OF THE MOUNTAINS.  
 

 
   
AVIATION
 
 
080930Z....COASTS/VALLEYS...LOW CLOUDS WILL CONTINUE TO GATHER  
ACROSS ALL COASTAL AREAS AND SOME OF THE VALLEYS THROUGH 14Z. BASES  
WILL BE 1000-1500 FEET MSL WITH TOPS TO 1900 FEET. VIS REDUCED 0-5SM  
INLAND. SCATTER OUT 16-19Z. AREAS OF LOW CLOUDS WITH BASES AROUND  
1500 FEET MSL WILL GRADUALLY DEVELOP AFTER 03Z INTO THURSDAY, BUT  
WITH LESS UNIFORM COVERAGE AND LESS INLAND EXTENT.  
 
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS TODAY AND  
TONIGHT.  
 

 
   
MARINE
 
 
WIND GUSTS AROUND 20 KT NEAR SAN CLEMENTE ISLAND THURSDAY AND FRIDAY  
AFTERNOONS AND EVENINGS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS  
THURSDAY THROUGH FRIDAY. LIGHTNING, ERRATIC WINDS, CHOPPY SEAS,  
AND/OR REDUCED VISIBILITY IN HEAVY RAIN LIKELY IN VICINITY OF ANY  
THUNDERSTORMS.  
 

 
   
BEACHES
 
 
THERE IS A 5-15% CHANCE OF THUNDERSTORMS PRODUCING LIGHTNING  
THURSDAY THROUGH FRIDAY.  
 

 
   
SKYWARN
 
 
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE  
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.  
 

 
   
SGX WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
PZ...NONE.  
 

 
 

 
 
PUBLIC...17  
AVIATION/MARINE/BEACHES...MM  
 
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