105
FXUS66 KSGX 171134
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
434 AM PDT THU SEP 17 2026
SYNOPSIS
HIGH TEMPERATURES WILL REMAIN AS MUCH AS 5 TO 10 DEGREES BELOW
AVERAGE FOR THE MOUNTAINS AND INLAND VALLEYS TODAY. HIGH
TEMPERATURES WILL WARM SLIGHTLY FOR FRIDAY AND A FEW TO AROUND 5
DEGREES ON SATURDAY, THEN COOL A FEW DEGREES EACH FOR SUNDAY AND
MONDAY. A WARMING TREND WILL BEGIN NEXT TUESDAY WITH HIGH
TEMPERATURES RETURNING TO AROUND AVERAGE ON WEDNESDAY. NIGHT AND
MORNING COASTAL LOW CLOUDS WILL SPREAD INLAND ACROSS MUCH OF THE
VALLEYS INTO THIS MORNING, THEN NOT AS FAR INTO THE VALLEYS THE
FOLLOWING NIGHTS AS THE MARINE LAYER BECOMES SHALLOWER.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
..UPDATED AVIATION DISCUSSION
SHORT TERM (TODAY THROUGH SATURDAY)
A LOW PRESSURE SYSTEM CENTERED ACROSS NORTHERN CALIFORNIA WILL
MAINTAIN HIGH TEMPERATURES AS MUCH AS 5 TO 10 DEGREES BELOW
AVERAGE FOR THE INLAND VALLEYS TODAY. THE LOW PRESSURE SYSTEM
WILL MOVE INLAND ON FRIDAY WITH WEAK HIGH PRESSURE MOVING ACROSS
CALIFORNIA ON SATURDAY. HIGH TEMPERATURES ON FRIDAY WILL WARM A
DEGREE OR TWO, THEN A FEW TO AROUND 5 DEGREES ON SATURDAY WITH THE
GREATEST WARMING FOR THE VALLEYS INTO THE MOUNTAINS. HIGH
TEMPERATURES ON SATURDAY WILL STILL BE A FEW DEGREES BELOW AVERAGE
WITH HIGH TEMPERATURES RANGING FROM THE 70S NEAR THE COAST TO THE
MID 80S TO LOWER 90S FOR THE INLAND EMPIRE WITH 100 TO 104 FOR
THE LOWER DESERTS.
THE MARINE LAYER IS AROUND 3500 FEET DEEP WITH COASTAL LOW CLOUDS
SPREADING INTO MUCH OF THE VALLEYS INTO THIS MORNING. THE MARINE
LAYER WILL BECOME GRADUALLY SHALLOWER FOR TONIGHT INTO THE WEEKEND
WITH NIGHT AND MORNING COASTAL LOW CLOUDS NOT SPREADING AS FAR
INTO THE VALLEYS FOR EARLY FRIDAY AND ONLY INTO THE FAR WESTERN
VALLEYS FOR EARLY SATURDAY.
LONG TERM (SUNDAY THROUGH WEDNESDAY)
A WEAK LOW PRESSURE SYSTEM OFF THE CALIFORNIA COAST ON SATURDAY
WILL MOVE SLOWLY INLAND INTO CALIFORNIA ON SUNDAY AND MONDAY WITH
NOT MUCH CHANGE IN HIGH TEMPERATURES ON SUNDAY. MONDAY HIGH
TEMPERATURES WILL COOL A FEW TO AROUND 5 DEGREES. HIGH PRESSURE TO
THE EAST WILL BRING WARMING FOR TUESDAY AND WEDNESDAY.
HIGH TEMPERATURES ON MONDAY WILL BE AS MUCH AS 4 TO 8 DEGREES
BELOW AVERAGE FOR THE VALLEYS INTO THE MOUNTAINS WITH HIGH
TEMPERATURES ON MONDAY RANGING FROM THE LOWER TO MID 70S NEAR THE
COAST TO THE LOWER TO MID 80S FOR THE INLAND EMPIRE WITH THE UPPER
90S FOR THE LOWER DESERTS.
HIGH TEMPERATURES ON WEDNESDAY WILL WARM TO WITHIN A FEW DEGREES
OF AVERAGE WITH THE HIGH TEMPERATURES RANGING FROM THE MID TO
UPPER 70S NEAR THE COAST TO THE UPPER 80S TO MID 90S FOR THE
INLAND EMPIRE WITH THE LOWER DESERTS AROUND 100.
AVIATION
171130Z...COAST/VALLEYS...LOW CLOUDS AROUND 2800-3500 FEET MSL FILL
THE COASTAL BASIN THIS MORNING. SOME FOOTHILLS OBSCURED IN CLOUDS
AND FG. SCATTER OUT BY 17-19Z. LOW CLOUDS BASED AROUND 2000-3000
FEET MSL WILL RETURN TO KSAN AND KCRQ BY 23-03Z BEFORE SPREADING
NORTH AND INTO THE ENTIRE COASTAL BASIN BY 12Z FRIDAY.
MOUNTAINS/DESERTS...MOSTLY CLEAR AND VFR CONDITIONS TODAY AND
TONIGHT.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH MONDAY.
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...MM
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