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FXUS66 KMTR [Monterey CA] 162039 AFDMTR 

FXUS66 KMTR 162039
AFDMTR [HEAD]

National Weather Service San Francisco Bay Area 1:39pm PDT Wed Jun 16 2021 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
139 PM PDT WED JUN 16 2021 [HEAD]

Synopsis. Dangerously hot and potentially life-threatening heat is forecast across the interior through late week as high pressure builds over the region. Meanwhile, onshore flow will limit heat impacts along the coastline and around the bays. Gradual cooling is then likely this weekend and more so into early next week. 

.SYNOPSIS...DANGEROUSLY HOT AND POTENTIALLY LIFE-THREATENING HEAT
IS FORECAST ACROSS THE INTERIOR THROUGH LATE WEEK AS HIGH
PRESSURE BUILDS OVER THE REGION. MEANWHILE, ONSHORE FLOW WILL
LIMIT HEAT IMPACTS ALONG THE COASTLINE AND AROUND THE BAYS.
GRADUAL COOLING IS THEN LIKELY THIS WEEKEND AND MORE SO INTO EARLY
NEXT WEEK. [DISC]

Discussion. As of 01:36pm PDT Wednesday… the much talked about heat for California, including the Bay Area, has arrived. First and foremost the Heat Advisory for interior locations went into effect at 11am this morning. A few spots started off on the cooler side this morning, but once the very warm airmass had a chance to mix in temperatures soared quickly. The most rapid warming occurred in locations with an offshore component. Perfect example was the Big Sur RAWS [Remote Automated Weather Station] spiking above 90° by 10am. Also interesting the rather large temp spread near the coast. In the city of the San Francisco temperatures reamin in the 60s at the beach and mid 80s near the castro. Therefore, did a temperature update today to boost temperatures a few degrees mainly near the coast/bays. The morning smoke/haze from fires to the east and south has dissipated a little bit per visible satellite. However, some smoke/haze will be possible again tonight depending on upstream fire activity. Any smoke that does make it here will be mainly elevated. 

.DISCUSSION...AS OF 01:36 PM PDT WEDNESDAY...THE MUCH TALKED
ABOUT HEAT FOR CALIFORNIA, INCLUDING THE BAY AREA, HAS ARRIVED.
FIRST AND FOREMOST THE HEAT ADVISORY FOR INTERIOR LOCATIONS WENT
INTO EFFECT AT 11 AM THIS MORNING. A FEW SPOTS STARTED OFF ON THE
COOLER SIDE THIS MORNING, BUT ONCE THE VERY WARM AIRMASS HAD A
CHANCE TO MIX IN TEMPERATURES SOARED QUICKLY. THE MOST RAPID
WARMING OCCURRED IN LOCATIONS WITH AN OFFSHORE COMPONENT. PERFECT
EXAMPLE WAS THE BIG SUR RAWS SPIKING ABOVE 90 DEGS BY 10 AM. ALSO
INTERESTING THE RATHER LARGE TEMP SPREAD NEAR THE COAST. IN THE
CITY OF THE SAN FRANCISCO TEMPERATURES REAMIN IN THE 60S AT THE
BEACH AND MID 80S NEAR THE CASTRO. THEREFORE, DID A TEMPERATURE
UPDATE TODAY TO BOOST TEMPERATURES A FEW DEGREES MAINLY NEAR THE
COAST/BAYS. THE MORNING SMOKE/HAZE FROM FIRES TO THE EAST AND
SOUTH HAS DISSIPATED A LITTLE BIT PER VISIBLE SATELLITE. HOWEVER,
SOME SMOKE/HAZE WILL BE POSSIBLE AGAIN TONIGHT DEPENDING ON
UPSTREAM FIRE ACTIVITY. ANY SMOKE THAT DOES MAKE IT HERE WILL BE
MAINLY ELEVATED. [DISC]

Tonight will be rather toasty in the hills with minor relief in the valleys. Would not be surprised one bit to see some temperatures stay in the 80s at a few spots in the hills. Overnight humidity recoveries will be on the poor side as well - less than 30% in the hills. Lastly, latest guidance continues to show some offshore flow (NE winds) in the hills. Not overly strong fortunately, but offshore nonetheless to heighten fire weather concerns. 

TONIGHT WILL BE RATHER TOASTY IN THE HILLS WITH MINOR RELIEF IN
THE VALLEYS. WOULD NOT BE SURPRISED ONE BIT TO SEE SOME
TEMPERATURES STAY IN THE 80S AT A FEW SPOTS IN THE HILLS.
OVERNIGHT HUMIDITY RECOVERIES WILL BE ON THE POOR SIDE AS WELL -
LESS THAN 30 PERCENT IN THE HILLS. LASTLY, LATEST GUIDANCE
CONTINUES TO SHOW SOME OFFSHORE FLOW (NE WINDS) IN THE HILLS. NOT
OVERLY STRONG FORTUNATELY, BUT OFFSHORE NONETHELESS TO HEIGHTEN
FIRE WEATHER CONCERNS. [DISC]

Thursday is stillon track to be the hottest day of the week and the peak of our heat event. Latest models show the airmass at 850 mb hitting near 28°C, which would be a daily record for KOAK [Oakland CA] sounding climatology. Made very little changes to ongoing forecast. Interior locations will be upgraded to a Excessive Heat Warning tomorrow, but North Bay/Santa Clara/N Salinas Valley and Santa Cruz Mountains remain an advisory. Forecast highs will be widespread triple digits across the interior with the hottest locations (Lake Berryessa, byron, Pinnacles national park, Bradly, fort hunter Liggett, Parkfield and Arroyo Seco) approaching or potentially exceeding 110°F. Still expecting cooler temperatures relatively speaking near the coast. However, temperatures will still be well above normal. In addition to the heat, forecast humidity values tomorrow are less than 10%. Factor in a little be of afternoon wind fire weather concerns increase. In addition to seeking relief from the heat don't be that spark that starts a fire. Two other items to note to watch for on Thursday will be a southerly surge and thunderstorms. Models have been suggesting the start of a surge creeping up the coast on Thursday, but northward progression looks to struggle against the NW winds off the coast. As for thunderstorms, upper level instability does increase (700–500 mb mu CAPE [Convective Available Potential Energy. A measure of the amount of energy available for convection. Related to the maximum potential vertical speed within an updraft; thus, higher values indicate greater potential for severe weather. Observed values in thunderstorm environments often may exceed 1000 joules per kilogram (J/kg), and in extreme cases may exceed 5000 J/kg.]), but any moisture is limited. In fact, some of the forecast soundings show a disconnect from the moisture and instability. Best way to put thunder chances is a non-zero chance. 

THURSDAY IS STILLON TRACK TO BE THE HOTTEST DAY OF THE WEEK AND
THE PEAK OF OUR HEAT EVENT. LATEST MODELS SHOW THE AIRMASS AT
850MB HITTING NEAR 28C, WHICH WOULD BE A DAILY RECORD FOR KOAK
SOUNDING CLIMATOLOGY. MADE VERY LITTLE CHANGES TO ONGOING
FORECAST. INTERIOR LOCATIONS WILL BE UPGRADED TO A EXCESSIVE HEAT
WARNING TOMORROW, BUT N BAY/SANTA CLARA/N SALINAS VALLEY AND SANTA
CRUZ MTS REMAIN AN ADVISORY. FORECAST HIGHS WILL BE WIDESPREAD
TRIPLE DIGITS ACROSS THE INTERIOR WITH THE HOTTEST LOCATIONS (LAKE
BERRYESSA, BYRON, PINNACLES NATIONAL PARK, BRADLY, FORT HUNTER
LIGGETT, PARKFIELD AND ARROYO SECO) APPROACHING OR POTENTIALLY
EXCEEDING 110 DEG F. STILL EXPECTING COOLER TEMPERATURES
RELATIVELY SPEAKING NEAR THE COAST. HOWEVER, TEMPERATURES WILL
STILL BE WELL ABOVE NORMAL. IN ADDITION TO THE HEAT, FORECAST
HUMIDITY VALUES TOMORROW ARE LESS THAN 10 PERCENT. FACTOR IN A
LITTLE BE OF AFTERNOON WIND FIRE WEATHER CONCERNS INCREASE. IN
ADDITION TO SEEKING RELIEF FROM THE HEAT DON`T BE THAT SPARK THAT
STARTS A FIRE. TWO OTHER ITEMS TO NOTE TO WATCH FOR ON THURSDAY
WILL BE A SOUTHERLY SURGE AND THUNDERSTORMS. MODELS HAVE BEEN
SUGGESTING THE START OF A SURGE CREEPING UP THE COAST ON
THURSDAY, BUT NORTHWARD PROGRESSION LOOKS TO STRUGGLE AGAINST THE
NW WINDS OFF THE COAST. AS FOR THUNDERSTORMS, UPPER LEVEL
INSTABILITY DOES INCREASE (700-500MB MU CAPE), BUT ANY MOISTURE IS
LIMITED. IN FACT, SOME OF THE FORECAST SOUNDINGS SHOW A
DISCONNECT FROM THE MOISTURE AND INSTABILITY. BEST WAY TO PUT
THUNDER CHANCES IS A NON-ZERO CHANCE. [DISC]

Another night of mild and dry conditions is expected Thursday night. 

ANOTHER NIGHT OF MILD AND DRY CONDITIONS IS EXPECTED THURSDAY
NIGHT. [DISC]

Thursday Heat Advisory and Excessive Heat Warning will continue into Friday as hot temperatures persist. One may notice a slight downward trend in temperatures on Friday, but factoring in the cumulative effect of hot weather heat related concerns will still exist. A gradual cooling trend is expected to occur during the upcoming weekend as the high pressure aloft weakens and onshore flow makes a greater push inland. However, temperatures look to remain well above seasonal averages at least into Sunday across the interior. 

THURSDAY HEAT ADVISORY AND EXCESSIVE HEAT WARNING WILL CONTINUE
INTO FRIDAY AS HOT TEMPERATURES PERSIST. ONE MAY NOTICE A SLIGHT
DOWNWARD TREND IN TEMPERATURES ON FRIDAY, BUT FACTORING IN THE
CUMULATIVE EFFECT OF HOT WEATHER HEAT RELATED CONCERNS WILL STILL
EXIST. A GRADUAL COOLING TREND IS EXPECTED TO OCCUR DURING THE
UPCOMING WEEKEND AS THE HIGH PRESSURE ALOFT WEAKENS AND ONSHORE
FLOW MAKES A GREATER PUSH INLAND. HOWEVER, TEMPERATURES LOOK TO
REMAIN WELL ABOVE SEASONAL AVERAGES AT LEAST INTO SUNDAY ACROSS
THE INTERIOR. [DISC]

Aviation. As of 10:40am PDT Wednesday… for the 18Z [11am PDT] TAFs [Terminal Aerodrome Forecasts]. Strong high pressure over the desert southwest is wrapping around high level moisture as well as mid level smoke into the region today. This is resulting in predominately VFR [Visual Flight Rules] however localized intermittent 4–6 sm haze/smoke will be possible through the day and return to impact most terminals by sunrise Thursday. Otherwise, passing high clouds through the day should not impact operations. A suppressed marine layer will generally remain away from TAF [Terminal Aerodrome Forecast] sites overnight, however, may see brief manifestation of few 002-few 004 near a few coastal sites, ie KMRY [Monterey CA]. Winds generally light/terrain driven through the morning becoming breezy to locally gusty onshore by the afternoon to early evening. A southerly surge reversal may bring a return of a thicker marine layer later Thursday into Friday though there is currently very low confidence on timing until later TAF [Terminal Aerodrome Forecast] packages. 

.AVIATION...AS OF 10:40 AM PDT WEDNESDAY...FOR THE 18Z TAFS.
STRONG HIGH PRESSURE OVER THE DESERT SOUTHWEST IS WRAPPING AROUND
HIGH LEVEL MOISTURE AS WELL AS MID LEVEL SMOKE INTO THE REGION
TODAY. THIS IS RESULTING IN PREDOMINATELY VFR HOWEVER LOCALIZED
INTERMITTENT 4-6SM HZ/FU WILL BE POSSIBLE THRU THE DAY AND RETURN
TO IMPACT MOST TERMINALS BY SUNRISE THURSDAY. OTHERWISE, PASSING
HIGH CLOUDS THROUGH THE DAY SHOULD NOT IMPACT OPERATIONS. A
SUPPRESSED MARINE LAYER WILL GENERALLY REMAIN AWAY FROM TAF SITES
OVERNIGHT, HOWEVER, MAY SEE BRIEF MANIFESTATION OF FEW002-FEW004
NEAR A FEW COASTAL SITES, IE KMRY. WINDS GENERALLY LIGHT/TERRAIN
DRIVEN THROUGH THE MORNING BECOMING BREEZY TO LOCALLY GUSTY
ONSHORE BY THE AFTERNOON TO EARLY EVENING. A SOUTHERLY SURGE
REVERSAL MAY BRING A RETURN OF A THICKER MARINE LAYER LATER
THURSDAY INTO FRIDAY THOUGH THERE IS CURRENTLY VERY LOW
CONFIDENCE ON TIMING UNTIL LATER TAF PACKAGES. [AVIA]

Vicinity of KSFO [San Francisco CA]VFR [Visual Flight Rules] through the period with increasing high clouds. Brief reductions to visibility due to passing haze/smoke. Lighter winds expected this afternoon compared to yesterday, though still breezy with gusts 20–25 kt [23–29 mph] possible. 

VICINITY OF KSFO...VFR THROUGH THE PERIOD WITH INCREASING HIGH
CLOUDS. BRIEF REDUCTIONS TO VISIBILITY DUE TO PASSING HZ/FU.
LIGHTER WINDS EXPECTED THIS AFTERNOON COMPARED TO YESTERDAY,
THOUGH STILL BREEZY WITH GUSTS 20-25 KT POSSIBLE. [AVI2]

SFO [San Francisco CA] bridge approach… similar to KSFO [San Francisco CA]

SFO BRIDGE APPROACH...SIMILAR TO KSFO. [AVI2]

Monterey Bay terminals… VFR [Visual Flight Rules] through the period with increasing high clouds. Brief reductions to visibility due to passing haze/smoke. Light winds this morning before the typical afternoon sea breeze returns in the afternoon. 

MONTEREY BAY TERMINALS...VFR THROUGH THE PERIOD WITH INCREASING
HIGH CLOUDS. BRIEF REDUCTIONS TO VISIBILITY DUE TO PASSING HZ/FU.
LIGHT WINDS THIS MORNING BEFORE THE TYPICAL AFTERNOON SEA BREEZE
RETURNS IN THE AFTERNOON. [AVI2]

Marine. As of 10:41am PDT Wednesday… gusty northwest winds will persist today and into tonight across the waters, strongest along the coastal jets. By Thursday, northwest winds will strengthen in the waters north of Point Reyes [San Francisco CA] with gale force gusts expected while weakening gradually elsewhere. These winds will generate steep northwest waves resulting in hazardous seas conditions, particularly for smaller vessels. Seas remain mainly wind driven with northwest waves at 8–10 seconds along with a marginal southerly swell. 

.MARINE...AS OF 10:41 AM PDT WEDNESDAY...GUSTY NORTHWEST WINDS
WILL PERSIST TODAY AND INTO TONIGHT ACROSS THE WATERS, STRONGEST
ALONG THE COASTAL JETS. BY THURSDAY,  NORTHWEST WINDS WILL
STRENGTHEN IN THE WATERS NORTH OF POINT REYES WITH GALE FORCE
GUSTS EXPECTED WHILE WEAKENING GRADUALLY  ELSEWHERE. THESE WINDS
WILL GENERATE STEEP NORTHWEST WAVES RESULTING IN HAZARDOUS SEAS
CONDITIONS, PARTICULARLY FOR SMALLER VESSELS. SEAS REMAIN MAINLY
WIND DRIVEN WITH NORTHWEST WAVES AT 8 TO 10 SECONDS ALONG WITH A
MARGINAL SOUTHERLY SWELL. [AVIA]

MTR Watches/Warnings/Advisories

  • Tonight: Heat Advisory…CAZ507–510–511–516>518 Heat Advisory…CAZ506–512–513–528 Small Craft AdvisoryPigeon Pt [Pescadero CA] to Pt Pinos [Monterey CA] 0–10 nm [11 miles] until 3am Small Craft AdvisoryPt Pinos [Monterey CA] to Pt Piedras Blancas [San Simeon CA] 0–10 nm [11 miles] until 3am Small Craft AdvisoryPt Arena [Mendocino CA] to Pigeon Pt [Pescadero CA] 10–60 nm [69 miles] until 3am GLWPt Arena [Mendocino CA] to Pigeon Pt [Pescadero CA] 10–60 nm [69 miles] from 3am Small Craft AdvisoryPt Arena [Mendocino CA] to Pt Reyes [San Francisco CA] 0–10 nm [11 miles] Small Craft AdvisoryPigeon Pt [Pescadero CA] to Pt Piedras Blancas [San Simeon CA] 10–60 nm [69 miles] Small Craft AdvisoryPt Reyes [San Francisco CA] to Pigeon Pt [Pescadero CA] 0–10 nm [11 miles] Small Craft Advisory…Monterey Bay until 9pm 
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...HEAT ADVISORY...CAZ507-510-511-516>518
HEAT ADVISORY...CAZ506-512-513-528
SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 AM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 AM
SCA...PT ARENA TO PIGEON PT 10-60 NM UNTIL 3 AM
GLW...PT ARENA TO PIGEON PT 10-60 NM FROM 3 AM
SCA...PT ARENA TO PT REYES 0-10 NM
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
SCA...PT REYES TO PIGEON PT 0-10 NM
SCA...MRY BAY UNTIL 9 PM [WARN]

Public Forecast: MM; Aviation: DRP; Marine: DRP 

PUBLIC FORECAST: MM
AVIATION: DRP
MARINE: DRP [CRED]
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO [LINK]

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Point Forecast

Half Moon Bay CA

16 Jun 02:55pm PDT

Tonight Mostly cloudy, with a low around 55°. NNW wind 10 to 15 mph becoming light. Winds could gust as high as 20 mph.
Thursday Mostly sunny, with a high near 80°. Light and variable wind becoming WNW 6 to 11 mph in the afternoon.
Thursday Night Partly cloudy, with a low around 53°. WSW wind 3 to 8 mph.
Friday Mostly sunny, with a high near 73°. Light west wind becoming WSW 5 to 9 mph in the morning.
Friday Night Partly cloudy, with a low around 53°. WSW wind 5 to 9 mph becoming light after midnight.
Saturday Mostly sunny, with a high near 71°.
Saturday Night Partly cloudy, with a low around 52°.
Sunday Mostly sunny, with a high near 69°.
Sunday Night Partly cloudy, with a low around 52°.
Monday Mostly sunny, with a high near 67°.
Monday Night Mostly cloudy, with a low around 53°.
Tuesday Mostly sunny, with a high near 66°.
Tuesday Night Mostly cloudy, with a low around 52°.
Wednesday Mostly sunny, with a high near 64°.
Tonight
Mostly cloudy, with a low around 55. North northwest wind 10 to 15 mph becoming light. Winds could gust as high as 20 mph.
Thursday
Mostly sunny, with a high near 80. Light and variable wind becoming west northwest 6 to 11 mph in the afternoon.
Thursday Night
Partly cloudy, with a low around 53. West southwest wind 3 to 8 mph.
Friday
Mostly sunny, with a high near 73. Light west wind becoming west southwest 5 to 9 mph in the morning.
Friday Night
Partly cloudy, with a low around 53. West southwest wind 5 to 9 mph becoming light after midnight.
Saturday
Mostly sunny, with a high near 71.
Saturday Night
Partly cloudy, with a low around 52.
Sunday
Mostly sunny, with a high near 69.
Sunday Night
Partly cloudy, with a low around 52.
Monday
Mostly sunny, with a high near 67.
Monday Night
Mostly cloudy, with a low around 53.
Tuesday
Mostly sunny, with a high near 66.
Tuesday Night
Mostly cloudy, with a low around 52.
Wednesday
Mostly sunny, with a high near 64.

This page is generated dynamically from the National Weather Service's NWS point forecast and Area Forecast Discussion, reformatted for readability. NWS glossary; about point forecasts. For more information, visit the Lobitos Weather Project home page. Comments and corrections are welcome: