439
FXUS66 KSTO 231920
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1220 PM PDT SAT MAY 23 2026
FOR ADDITIONAL DETAILS ON WEATHER AND EXPECTED IMPACTS OVER THE
NEXT 7 DAYS, PLEASE VISIT WEATHER.GOV/STO/BRIEFING.
KEY MESSAGES
- COOLING TREND THROUGH EARLY NEXT WEEK.
- GUSTY SOUTHWESTERLY WINDS THROUGH MONDAY COMBINED WITH LOW
DAYTIME RHS, WILL LEAD TO ELEVATED FIRE WEATHER CONDITIONS IN
THE VALLEY.
- ELEVATED FIRE WEATHER CONDITIONS IN THE VALLEY TUESDAY-
WEDNESDAY DUE TO GUSTY NORTH WINDS AND LOW HUMIDITY.
- CHANCES FOR ISOLATED SHOWERS/THUNDERSTORMS TUESDAY-THURSDAY
AFTERNOON AND EVENING OVER THE SIERRA AND SHASTA COUNTY.
DISCUSSION
..TODAY THROUGH MONDAY
CURRENT SATELLITE HAS CLEAR SKIES ACROSS THE AREA, WITH 5-15MPH
WINDS. TEMPERATURES ARE EXPECTED TO REACH INTO THE 80S TO LOW 90S
TODAY, WITH MINIMUM RH VALUES IN THE UPPER TEENS TO 20S WITHIN
THE VALLEY AND PORTIONS OF THE SIERRA. WINDS WILL BE BREEZY AT
TIMES THIS AFTERNOON OUT OF THE SOUTHWEST. THIS COMBINED WITH THE
LOW RH VALUES BRING PERIODS OF ELEVATED FIRE WEATHER CONDITIONS
FOR THE VALLEY WHERE THE WINDS ARE HIGHEST.
TEMPERATURES REMAIN WARM SUNDAY AND INTO MONDAY, WITH THE WARMEST
CONDITIONS IN THE NORTHERN SACRAMENTO VALLEY AND INTO PORTIONS OF
THE NORTHERN SAN JOAQUIN VALLEY. AN APPROACHING LOW PRESSURE
SYSTEM FROM THE EASTERN PACIFIC WILL HELP BRING DOWN TEMPERATURES
IN THE SOUTHERN SACRAMENTO VALLEY AND INTO THE DELTA BY MONDAY.
HIGHS ON MONDAY WILL BE IN THE 70S TO LOWER 80S IN PORTIONS OF THE
SOUTHERN SACRAMENTO VALLEY AND THROUGH THE DELTA THANKS TO
ONSHORE FLOW FROM THE APPROACHING SYSTEM. OTHER AREAS WILL
CONTINUE TO SEE UPPER 80S TO LOWER 90S.
WINDS REMAIN BREEZY SUNDAY OUT OF THE SW, BUT AS THE LOW PRESSURE
MOVES CLOSER TO THE REGION MONDAY WINDS DO INCREASE. WINDS HAVE
THE POTENTIAL TO GUST 25-35 MPH MONDAY. THIS COMBINED WITH LOW RH
VALUES IN THE VALLEY BRING ELEVATED FIRE WEATHER CONDITIONS.
PLEASE DO BE MINDFUL OF ANY HOLIDAY WEEKEND ACTIVITIES THAT
INVOLVE FIRE/FLAME; THE FUELS WILL ONLY CONTINUE TO DRY AS WE DIVE
INTO THE DRY SEASON.
..TUESDAY THROUGH FRIDAY
THE UPPER LEVEL SYSTEM MOVES ONSHORE AND THROUGH THE REGION
TUESDAY THROUGH THURSDAY SWITCHING THE WINDS FROM THE SOUTHWEST
TOWARD THE NORTH TO NORTHEAST. AS THIS HAPPENS WE INCREASE OUR
WINDS, WITH GUSTS 35-45 MPH POSSIBLE TUESDAY AND WEDNESDAY WITHIN
THE VALLEY. DRIER AIR IS FILTERED INTO THE VALLEY HELPING TO LOW
DAYTIME RH VALUES INTO THE TEENS. LOCALIZED LOWER RH VALUES ARE
POSSIBLE IN THE NORTHERN SACRAMENTO VALLEY. RIGHT NOW, WE ARE
LOOKING AT ELEVATED FIRE WEATHER CONDITIONS TUESDAY EVENING
THROUGH WEDNESDAY WHEN THE WINDS ARE THE HIGHEST AND COMBINED
WITH LOW RH VALUES. CONFIDENCE IN THE TEMPORAL RESOLUTION OF RFW
CONDITIONS ARE LOWER AS CRITERIA ISN'T REACHED ON A CONSISTENT
BASIS. NONE THE LESS, CONFIDENCE IS INCREASING ON THE ELEVATED
FIRE WEATHER CONCERNS IN GENERAL AND WE WILL CONTINUE TO MONITOR
THE NEED FOR ANY PRODUCTS FOR TUESDAY THROUGH WEDNESDAY AS WE
PUSH THROUGH THE WEEKEND.
ON TOP OF FIRE WEATHER CONDITIONS, WE HAVE THE CHANCE FOR ISOLATED
SHOWERS AND STORMS WITHIN THE SIERRA AND PARTS OF SHASTA COUNTY
TUESDAY THROUGH THURSDAY. A FEW HIGHER BASED STORMS ARE POSSIBLE
WITH 15-25 PERCENT CHANCES (HIGHEST IN THE SIERRA SOUTH OF HIGHWAY
50). CONFIDENCE REMAINS LOW ON TIMING, STRENGTH, AND DEVELOPMENT
OF THESE STORMS AS WE HAVE LIMITED MOISTURE AND INSTABILITY AS THE
LOW PRESSURE MOVES THROUGH. TEMPERATURES WILL START TO WARM DURING
THIS TIME AND REACH BACK INTO THE UPPER 80S FOR THE VALLEY BY THE
END OF THE WEEK AS A HIGH PRESSURE BUILDS INTO THE REGION.
AVIATION
VFR CONDITIONS ARE EXPECTED FOR THE TAF PERIOD. SOUTH TO
SOUTHWESTERLY WINDS INCREASE THROUGH THE AFTERNOON FOR THE
SACRAMENTO SITES, WITH NORTHERLY WINDS IN SCK AND MOD. WINDS HAVE
THE POTENTIAL TO GUST UP TO 20KTS THIS AFTERNOON AND EVENING FOR
THE SACRAMENTO SITES. AROUND 6Z WINDS START TO GO LIGHT AND
VARIABLE, WITH CLEAR SKIES OVERNIGHT.
STO WATCHES/WARNINGS/ADVISORIES
NONE.
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