659
FXUS66 KSGX 170403
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
903 PM PDT MON MAR 16 2026
SYNOPSIS
HOT CONDITIONS WITH WELL ABOVE AVERAGE TEMPERATURES EXPECTED THIS
WEEK. WEAK OFFSHORE FLOW IS EXPECTED TODAY AND TOMORROW, WITH EAST
TO NORTHEAST WIND GUSTS 25 TO 40 MPH ALONG AND BELOW THE COASTAL
SLOPES OF THE MOUNTAINS. SOME COOLING IS EXPECTED THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. EVEN WITH THE COOLING HIGH
TEMPERATURES FOR INLAND AREAS STILL 10 TO 15 DEGREES ABOVE AVERAGE.
MARINE LAYER LOW CLOUDS AND FOG WILL BE LARGELY ABSENT FROM THE
COAST THIS WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: WEAK OFFSHORE WINDS ARE SLOWLY STARTING TO RETURN TO THE
COAST AT THIS HOUR, WHICH HAS HELPED TO PUSH OUT THE LOW CLOUD
DECK/FOG BANK ALONG PORTIONS OF THE SAN DIEGO COASTLINE THIS
EVENING. THESE WEAK OFFSHORE WINDS SHOULD HELP TO KEEP THE MARINE
LAYER MOSTLY CONFINED TO JUST THE COASTAL AREAS, WITH MINIMAL
COVERAGE OVER LAND WITHIN 5 MILES FROM THE COAST. OTHER THAN SOME
PASSING HIGH CLOUDS, THE REST OF THE REGION SHOULD OBSERVE MOSTLY
CLEAR SKIES. THE RIDGE OVERHEAD WILL CONTINUE TO STRENGTHEN
THROUGHOUT THE WEEK, WITH THE RIDGE PEAKING OUT IN INTENSITY BY
THURSDAY INTO FRIDAY. NOT ONLY ARE TEMPERATURES EXCEPTIONALLY WARM,
GIVEN THE TIME OF YEAR, BUT THE DURATION OF PROLONGED HEAT FOR
WIDESPREAD LOCATIONS IS WHAT IS MAKING THIS AN UNPRECEDENTED HEAT
WAVE, ESPECIALLY FOR THIS TIME OF YEAR. BY THURSDAY, IT IS POSSIBLE
THAT THERE WILL BE A FEW LOCATIONS POSSIBLY BREAKING MONTHLY
RECORDS, AND THEN AGAIN ON FRIDAY. WE WILL FINALLY BEGIN TO SEE SOME
RELIEF FROM THIS HEAT BEGINNING THIS UPCOMING WEEKEND; GRADUALLY
COOLING FROM WEST TO EAST. THIS WILL OCCUR AS THE RIDGE BEGINS TO
FINALLY WEAKEN WITH MORE TROUGHING INFLUENCING THE REGION. BE SURE
TO STAY ALERT TO ANY UPDATES TO OUR HEAT WATCHES AND ADVISORIES
AT WEATHER.GOV/SGX/
PREVIOUS DISCUSSION SUBMITTED AT 1116 AM:
A PERSISTENT ANOMALOUSLY STRONG UPPER LEVEL AREA OF HIGH PRESSURE IS
EXPECTED OVER SOUTHERN CALIFORNIA THIS WEEK. THE HIGH IS EXPECTED TO
BE AT ITS STRONGEST THURSDAY AND FRIDAY, WITH THE POTENTIAL FOR 500
MB HEIGHT RECORDS TO BE BROKEN FOR THE MONTH OF MARCH. MOST DAYS
THIS WEEK HAVE THE POTENTIAL FOR DAILY TEMPERATURE RECORDS TO BE
BROKEN OR TIED, WITH THE POTENTIAL FOR MONTHLY TEMPERATURE RECORDS
TO BE BROKEN OR TIED WEDNESDAY THROUGH FRIDAY. SEE THE CLIMATE
SECTION BELOW FOR MORE INFORMATION.
FOR TODAY AND TUESDAY, WEAK EAST TO NORTHEASTERLY WINDS ARE
EXPECTED. PEAK GUSTS OF 25 TO 40 MPH ARE EXPECTED ON THE COASTAL
MOUNTAIN FOOTHILLS AND BELOW PASSES. STRONGEST WINDS ARE EXPECTED ON
TUESDAY. WEAK OFFSHORE FLOW, COMBINED WITH THE BUILDING RIDGE ALOFT
WILL RESULT IN WARMER CONDITIONS FOR THE COAST AND VALLEYS. HIGH
TEMPERATURES AT THE COAST AND WESTERN VALLEYS WILL PEAK ON TUESDAY.
WIDESPREAD MODERATE TO LOCALLY MAJOR HEATRISK ARE EXPECTED. REDUCE
OUTDOOR ACTIVITIES IF POSSIBLE BETWEEN 10 AM AND 5 PM, SEEK SHADE,
AND STAY HYDRATED. ON WEDNESDAY, A WEAK COASTAL EDDY COULD BRING A
FEW DEGREES OF COOLING FOR INLAND COASTAL AREAS INTO THE WESTERN
VALLEYS WITH THE MOUNTAINS AND DESERTS WARMING ANOTHER 3 TO 5
DEGREES.
THE HEAT IS EXPECTED TO PEAK FOR MOST INLAND AREAS ON THURSDAY OR
FRIDAY. WIDESPREAD MODERATE TO AREAS OF MAJOR HEATRISK ARE EXPECTED.
HIGH TEMPERATURES WILL BE 20 TO 30 DEGREES ABOVE AVERAGE FOR THIS
TIME OF YEAR. DAILY AND MONTHLY TEMPERATURE RECORDS ARE EXPECTED TO
BE BROKEN OR TIED FOR LOCATIONS LIKE RAMONA, BIG BEAR LAKE,
IDYLLWILD, PALM SPRINGS, AND BORREGO SPRINGS. OVERNIGHT LOWS WILL
ALSO BE ELEVATED, WHICH WILL LIMIT OVERNIGHT RELIEF FROM THE HEAT.
THE CURRENTLY FORECAST LOW TEMPERATURES FOR IDYLLWILD OF 64 FOR BOTH
FRIDAY AND SATURDAY WOULD BE THE EARLIEST FOR SUCH A WARM LOW
TEMPERATURE AT IDYLLWILD BY ALMOST THREE MONTHS, THE CURRENT
EARLIEST DATE FOR SUCH A WARM LOW TEMPERATURE BEING JUNE 16TH (2021).
WEAKENING HIGH PRESSURE ALOFT AND ONSHORE FLOW WILL BEGIN TO SPREAD
COOLING INLAND AS EARLY AS SATURDAY FOR PLACE WEST OF THE MOUNTAINS,
WITH COOLING SPREADING INLAND SUNDAY AND MONDAY. EVEN WITH THE
COOLING HIGH TEMPERATURES FOR INLAND AREAS FOR MONDAY OF NEXT WEEK
STILL 10 TO 15 DEGREES ABOVE AVERAGE. MUCH OF THIS WEEK WILL SEE AN
ABSENCE OF MARINE LAYER LOW CLOUDS AND FOG, WITH THE POTENTIAL FOR
CLOUDS AND FOG TO RETURN LATE IN THE WEEKEND OR EARLY NEXT WEEK.
AVIATION
170600Z...COASTS...DECK OF LOW CLOUDS AROUND 200-300FT MSL LINGERING
OFFSHORE OF SAN DIEGO COUNTY THIS EVENING. PATCHY LOW CLOUDS REMAINS
POSSIBLE OUT OVER THE WATERS AND JUST OFFSHORE THROUGH THE OVERNIGHT
HOURS, WITH A LOW CHANCE (<10%) OF IMPACTING ANY TAF SITES.
SIMILARLY PATCHY LOW CLOUDS ARE POSSIBLE AGAIN ALONG THE COASTS
AFTER 02Z WEDNESDAY.
VALLEYS/MOUNTAINS/DESERTS...OFFSHORE WINDS HAVE LARGELY WANED THIS
EVENING FOR THE VALLEYS, THOUGH NORTH-NORTHEASTERLY GUSTS 15-20 KTS
REMAIN POSSIBLE THROUGH THE OVERNIGHT HOURS FOR THE MOUNTAINS AND
PASSES. OFFSHORE WINDS TURN MORE EASTERLY ON TUESDAY, WITH GUSTS TO
20-25 KTS POSSIBLE AFTER 12Z TUESDAY, MOSTLY IN AND JUST BELOW
MOUNTAIN PASSES.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH
FRIDAY.
BEACHES
A LONG PERIOD (17-19 SECOND) SOUTH-SOUTHWESTERLY SWELL (190-200
DEGREES) BUILDS OVERNIGHT, BRINGING BREAKING WAVES OF 3-6 FEET, WITH
SETS UP TO 7 FEET ON SOUTH-FACING BEACHES. SWELL AND ASSOCIATED SURF
DECREASES ON WEDNESDAY. LOCALLY HAZARDOUS SWIMMING CONDITIONS ARE
EXPECTED. A BEACH HAZARDS STATEMENT CONTAINS MORE DETAILS.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY EVENING FOR ORANGE
COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.
HEAT ADVISORY UNTIL 8 PM PDT FRIDAY FOR ORANGE COUNTY COASTAL
AREAS-ORANGE COUNTY INLAND AREAS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
COASTAL AREAS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS
AND FOOTHILLS.
HEAT ADVISORY FROM 10 AM WEDNESDAY TO 8 PM PDT FRIDAY FOR
RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-
SAN DIEGO COUNTY MOUNTAINS.
EXTREME HEAT WARNING FROM 10 AM WEDNESDAY TO 8 PM PDT SATURDAY
FOR COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS-SAN GORGONIO
PASS NEAR BANNING.
PZ...NONE.
PUBLIC...CO
AVIATION/MARINE/BEACHES...MUNYAN
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