591
FXUS66 KSGX 181545
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
845 AM PDT WED JUN 18 2025
SYNOPSIS
HIGH PRESSURE ALOFT WILL CONTINUE HIGH TEMPERATURES AS MUCH AS 8
TO 12 DEGREES ABOVE AVERAGE TODAY FOR THE MOUNTAINS, DESERTS, AND
INLAND VALLEYS. FOR THURSDAY THROUGH THE WEEKEND, THERE WILL BE A
COOLING TREND WITH WEEKEND HIGH TEMPERATURES AS MUCH AS 5 TO 10
DEGREES BELOW AVERAGE FOR THE MOUNTAINS DURING THE WEEKEND. THE
MARINE LAYER WILL DEEPEN WITH NIGHT AND MORNING COASTAL LOW CLOUDS
SPREADING FARTHER INTO THE VALLEYS. THERE MAY BE WARMING OF
AROUND 5 DEGREES FOR EARLY NEXT WEEK BUT WITH HIGH TEMPERATURES
REMAINING BELOW AVERAGE.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
MORNING UPDATE
LOW CLOUDS CONTINUE TO RETREAT TOWARD THE BEACHES, WHICH WILL
CLEAR LATER THIS MORNING. WE WILL SEE ONE MORE DAY OF HOT
TEMPERATURES INLAND, WITH A COOLING TREND BEGINNING BY THURSDAY.
THE MARINE LAYER WILL DEEPEN SLIGHTLY TONIGHT, BRINGING A GREATER
CHANCE OF LOW CLOUDS TO BOTH VALLEYS OF SAN DIEGO AND ORANGE
COUNTIES. THE WEEKEND WILL SEE THE COOLEST DAYS OVERALL WITH
SUBTLE WARMING BY THE MIDDLE OF NEXT WEEK. OTHERWISE, NO FORECAST
CHANGES THIS MORNING.
SHORT TERM (TODAY THROUGH FRIDAY)
HIGH TEMPERATURES FOR THE MOUNTAINS WILL WARM AROUND 5 DEGREES
TODAY WITH SLIGHT COOLING FOR THE WESTERN VALLEYS AND INLAND
COASTAL AREAS. HIGH TEMPERATURES FOR TODAY WILL BE AS MUCH AS 8 TO
12 DEGREES ABOVE AVERAGE FOR THE MOUNTAINS, DESERTS, AND INLAND
VALLEYS RANGING FROM THE LOWER 70S NEAR THE COAST TO THE 90S TO
AROUND 100 FOR THE INLAND EMPIRE WITH 112 TO 116 FOR THE LOWER
DESERTS.
FOR THURSDAY INTO THE WEEKEND, A LOW PRESSURE SYSTEM OVER THE
EASTERN PACIFIC WILL MOVE SLOWLY INTO THE WESTERN STATES. THIS
WILL STRENGTHEN THE ONSHORE FLOW ACROSS SOUTHERN CALIFORNIA AND
WEAK HIGH PRESSURE ALOFT. THIS WILL SPREAD COOLING INLAND WITH
COOLING ON THURSDAY OF A FEW DEGREES TO AROUND 5 DEGREES FOR THE
MOUNTAINS AND INLAND VALLEYS WITH SLIGHTLY GREATER ADDITIONAL
COOLING ON FRIDAY.
WITH THE COOLING, FRIDAY HIGH TEMPERATURES WILL BE AROUND 5
DEGREES BELOW AVERAGE FOR THE MOUNTAINS, BUT STILL AROUND 5
DEGREES ABOVE AVERAGE FOR THE LOWER DESERTS. HIGH TEMPERATURES ON
FRIDAY WILL RANGE FROM AROUND 70 NEAR THE COAST TO THE 80S TO
AROUND 90 FOR THE INLAND EMPIRE WITH 105 TO 110 FOR THE LOWER
DESERTS.
THE MARINE LAYER WILL BEGIN TO DEEPEN, TO 1500 TO 2000 FEET FOR
FRIDAY WITH NIGHT AND MORNING COASTAL LOW CLOUDS SPREADING INTO
PORTIONS OF THE WESTERN VALLEYS.
LONG TERM (SATURDAY THROUGH TUESDAY)
THE COOLING WILL CONTINUE INTO THE WEEKEND WITH WEEKEND HIGH
TEMPERATURES A FEW DEGREES BELOW AVERAGE NEAR THE COAST TO 5 TO 10
DEGREES BELOW AVERAGE FOR THE MOUNTAINS AND VALLEYS WITH HIGH
TEMPERATURES RANGING FROM AROUND 70 NEAR THE COAST TO THE UPPER
70S TO UPPER 80S FOR THE INLAND EMPIRE WITH THE UPPER 90S TO
AROUND 100 FOR THE LOWER DESERTS. THE MARINE LAYER WILL DEEPEN TO
2000 TO 2500 FEET WITH NIGHT AND MORNING COASTAL LOW CLOUDS
SPREADING FARTHER INTO THE VALLEYS.
FOR MONDAY AND TUESDAY, HIGH TEMPERATURES MAY WARM AROUND 5
DEGREES, BUT REMAIN BELOW AVERAGE WITH NIGHT AND MORNING COASTAL
LOW CLOUDS SPREADING INTO PORTIONS OF THE VALLEYS.
AVIATION
181530Z....COAST/WESTERN VALLEYS...MOSTLY CLEAR SKIES TODAY BUT WITH
PATCHES OF LOW CLOUDS ON THE IMMEDIATE COAST. LOW CLOUDS TO
REDEVELOP AFTER 02Z, EXTENDING FARTHER INLAND OVERNIGHT INTO
THURSDAY. BASES SHOULD BE 700-1000 FEET MSL AND VIS 1-5SM OVER
HIGHER COASTAL TERRAIN AND WESTERN VALLEYS.
INLAND VALLEYS/MOUNTAINS/DESERTS
CLEAR SKIES AND UNRESTRICTED VIS
THROUGH THURSDAY MORNING.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH SUNDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
INLAND AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
MOUNTAINS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS AND
FOOTHILLS.
PZ...NONE.
PUBLIC...APR
AVIATION/MARINE...MM
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