708  
FXUS66 KSGX 041646  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
946 AM PDT SAT OCT 4 2025  
   
SYNOPSIS
 
 
WEAK OFFSHORE WINDS THIS MORNING WILL GIVE WAY TO THE TYPICAL SEA  
BREEZE WEST OF THE MOUNTAINS IN THE AFTERNOON. TEMPERATURES THIS  
AFTERNOON WILL BE WARMER THAN YESTERDAY OUTSIDE OF THE IMMEDIATE  
COAST AND LOW DESERTS, BUT STILL NEAR TO BELOW THE DAILY AVERAGE.  
DAILY MARINE LAYER CLOUDS WILL LIKELY MAKE A COMEBACK EARLY SUNDAY  
MORNING, WITH MORE WIDESPREAD LOW CLOUDS EARLY NEXT WEEK. LITTLE  
CHANGE IN TEMPERATURES THROUGH MONDAY, FOLLOWED BY A GRADUAL  
WARMING TREND INTO THE MIDDLE/LATTER PART OF NEXT WEEK. THERE IS  
THE POTENTIAL FOR TROPICAL MOISTURE TO MOVE INTO THE AREA LATE IN  
THE WEEK, BRINGING A SLIGHT CHANCE OF SHOWERS, MOSTLY OVER THE  
MOUNTAINS.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
   
SHORT TERM
 
 
THE UPPER LEVEL LOW THAT BROUGHT COOLER TEMPERATURES AND BREEZY  
WINDS TO THE REGION YESTERDAY HAS MOVED TO THE NORTHEAST INTO THE  
INTERMOUNTAIN WEST THIS MORNING, LEAVING US IN BROAD, WEAK  
TROUGHING. AS A RESULT, WINDS ARE CALM OUTSIDE OF A FEW TYPICALLY  
WINDY GAPS LIKE THE BANNING PASS INTO THE NORTHERN COACHELLA  
VALLEY AND THROUGH THE IN-KO-PAH GORGE JUST EAST OF THE SAN DIEGO  
COUNTY LINE, WHICH ARE STILL SEEING GUSTS TO 20-30 MPH. ELSEWHERE,  
THE MOVEMENT OF THE LOW HAS RESULTED IN WEAK OFFSHORE (GENERALLY  
NORTH TO NORTHEAST) FLOW. THIS IS CONTRIBUTING TO THE MOSTLY CLEAR  
SKIES IN THE AREA, OUTSIDE OF A SCATTERING DECK AROUND 1500 FEET  
IN THE MORE SHELTERED INLAND EMPIRE AND NORTHERN ORANGE COUNTY.  
 
MORE TYPICAL, MILD SOCAL WEATHER IS EXPECTED TODAY INTO EARLY NEXT  
WEEK. WINDS WILL SHIFT TO THE WEST STARTING AT THE COAST EARLY  
THIS AFTERNOON AS THE SEA BREEZE DEVELOPS, THEN MOVE INLAND INTO  
THE LATE AFTERNOON. HIGH TEMPERATURES TODAY WILL BE A FEW DEGREES  
(2-4 F) ABOVE YESTERDAY'S OUTSIDE OF THE IMMEDIATE COAST AND LOW  
DESERTS, WHERE TEMPERATURES WILL BE ABOUT THE SAME AS YESTERDAY TO  
EVEN A TAD COOLER. DESPITE THIS MILD WARMUP, TEMPERATURES REMAIN  
NEAR (ALONG THE COAST) TO 5 TO 10 DEGREES BELOW THE DAILY AVERAGE  
TEMPERATURE.  
 
A BROAD TROUGH REMAINS OVER THE WESTERN U.S. INTO EARLY NEXT  
WEEK, AND A SHORTWAVE DIGGING DOWN THE WESTERN SIDE OF THE TROUGH  
WILL DEVELOP INTO A WEAK LOW OFF THE SOUTH-CENTRAL CALIFORNIA  
COAST. THIS WILL RESULT IN A VERY SUBTLE COOLING TREND SUNDAY  
THROUGH MONDAY FOR MOST OF SOUTHWEST CALIFORNIA, BUT IN PRACTICE  
TEMPERATURES WILL STILL BE VERY SIMILAR TO TODAY. HOWEVER, IT  
WILL SHIFT THE FLOW TO A MORE ONSHORE REGIME, WHICH WILL BRING  
NIGHTLY AND MORNING LOW CLOUDS BACK TO OUR COASTAL AREAS. LOW  
CLOUDS WILL STRUGGLE TO FORM MOST OF TONIGHT, BUT AN EDDY  
CIRCULATION DEVELOPING EARLY SUNDAY MORNING WILL MOISTEN THINGS UP  
ENOUGH TO GET AT LEAST PATCHY LOW CLOUDS ALONG THE SAN DIEGO AND  
LIKELY NORTHERN ORANGE COUNTY COASTLINE. LOW CLOUDS SUNDAY AND  
MONDAY NIGHTS WILL BE EARLIER TO DEVELOP AND MORE WIDESPREAD.  
 

 
   
LONG TERM
 
 
THE WEAK CLOSED LOW WILL OPEN INTO THE BROADER TROUGH AND MOVE TO  
THE NORTHEAST LATE TUESDAY INTO WEDNESDAY AS THE WEST END OF A  
BROAD HIGH OVER THE SOUTHERN U.S. NUDGES INTO THE AREA. THIS WILL  
RESULT IN A WARMING TREND TUESDAY THROUGH THE MID TO LATTER HALF  
OF NEXT WEEK. MEANWHILE, A LARGE LOW PRESSURE SYSTEM WILL DROP  
SOUTH OUT OF THE GULF OF ALASKA AND MAKE ITS WAY DOWN THE WEST  
COAST. SIMULTANEOUSLY, A DEVELOPING TROPICAL SYSTEM SOUTH OF BAJA  
CALIFORNIA WILL GRADUALLY MAKE ITS WAY NORTHWEST THROUGH NEXT  
WEEK, LIKELY LEADING TO SOME AMOUNT OF REMNANT MOISTURE MOVING  
INTO SOUTHERN CALIFORNIA BY LATE THURSDAY/FRIDAY.  
 
THERE IS SIGNIFICANT DIFFERENCES IN MODEL OUTPUT FOR WHERE THE  
LOW FROM THE NORTHWEST WILL SET UP, AS WELL AS THE TRACK OF THE  
TROPICAL SYSTEM ALONG WITH HOW MUCH MOISTURE FROM IT WILL ADVECT  
INTO THE AREA, LEADING TO A LOW CONFIDENCE FORECAST FOR BOTH  
TEMPERATURES AND POSSIBLE CONVECTIVE RAINFALL FOR THE LATTER PART  
OF NEXT WEEK. FOR NOW, THE FORECAST IS FOR NEAR ZERO CHANCES FOR  
RAINFALL INCREASING TO A SMALL CHANCE (10-15%) BY LATE THURSDAY,  
THEN WITH SLIGHT CHANCES (15-20%) OVER THE MOUNTAINS AND PARTS OF  
THE DESERTS AND LESS THAN 15% CHANCES ELSEWHERE FRIDAY AND  
SATURDAY. MOISTURE WOULD BE FAIRLY HIGH-BASED, RESULTING IN THOSE  
HIGHER CHANCES OVER THE MOUNTAINS, BUT IF WE GET STRONG ENOUGH  
FORCING FROM TROUGHING NEARBY, SHOWERS WEST OF THE MOUNTAINS  
WOULD NOT BE OUT OF THE QUESTION, AS INDICATED BY A HANDFUL OF  
ENSEMBLE MEMBERS. CURRENTLY INSTABILITY APPEARS TOO WEAK TO  
INCLUDE ANY THUNDERSTORMS IN THE FORECAST.  
 

 
   
AVIATION
 
 
041600Z....COASTS/VALLEYS...PATCHY LOW CLOUDS WITH BASES 1500-3000  
FT MSL WILL SCATTER OR CLEAR BY 17Z. PATCHES OF LOW CLOUDS MAY  
DEVELOP AFTER 03Z SUN. LESS THAN 30% CHANCE FOR CIGS AT COASTAL TAF  
SITES BEFORE 12Z SUN. ANY CLOUDS THAT DEVELOP WILL BE PATCHY IN  
COVERAGE WITH BASES 1500-2500 FT MSL.  
 
MOUNTAINS/DESERTS...VFR CONDITIONS WILL PREVAIL INTO SUN.  
 

 
   
MARINE
 
 
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH WEDNESDAY  
MORNING.  
 

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

 
 

 
 
PUBLIC...CSP  
AVIATION/MARINE...CO  
 
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