Marine Weather and Tide Forecast for Los Altos Hills, CA

UPDATE
Issued at 927 AM PDT Sun Apr 20 2025

Clear conditions expected to persist this afternoon. Highs are forecast to reach the low to mid 70s across the interior and upper 50s to mid 60s along the coast. No changes to the forecast at this time.

SHORT TERM
(Today and tonight and Monday )
Issued at 228 PM PDT Sun Apr 20 2025

The stratus blanketing the Bay Area and Central Coast has receded much faster today than it has over the past few days. For example, stratus did recede from Santa Rosa until after 3PM yesterday but cleared completely by 1PM today. The 24 hour temperature change shows temperatures are running on average 5 to 10 degrees warmer today than they were at this time yesterday as a result of the much more rapid clearing of stratus today. A few sites across areas of elevated terrain are even running up to 15 degrees warmer today than they were yesterday! That being said, we did nudge high temperatures across the North Bay Valleys down by a few degrees (changing the forecast high from the low 70s to the upper 60s) in order to account for stratus lingering longer across the NB Valleys than it did across the rest of the region. In general, temperatures will be fairly seasonal today with highs in the upper 60s to mid 70s across the interior. Cooler coastal temperatures prevail with highs in the upper 50s to low 60s.
Temperatures are expected to rise further on Monday as zonal flow develops with high temperatures in the mid 70s to low 80s across the interior and low to mid 60s along the coast. Building high pressure and zonal upper level flow will help to compress the marine layer to around 500 to 1000 ft overnight tonight. This should serve to limit inland stratus intrusion overnight and keep stratus confined more closely to the shoreline/coastal areas.

LONG TERM
(Monday night through Saturday)
Issued at 228 PM PDT Sun Apr 20 2025

Zonal flow persists through Tuesday with temperatures remaining seasonal to slightly above normal in the mid to upper 70s for interior locations and low to mid 60s along the coast. Heading into Wednesday, a weak shortwave trough will move in and kick start a cooling trend across the region. This will allow temperatures to cool into the upper 60s to low 70s across the interior and mid 50s to low 60s along the coast. This system is not expected to produce any precipitation with it but may result in some locally breezy winds. Current NBM and local high resolution WRF guidance keep the highest gusts out over the marine environment but gusts between 20 to 30 mph are possible across the higher terrain. The cooling trend continues Thursday into the weekend with high temperatures dropping into the low to mid 60s across the interior and mid 50s to low 60s along the coast.
Heading into Friday, a deeper upper level trough will move into the West Coast and bring a low chance for light rain to northernmost portions of the Sonoma and Napa Counties. At most, this system looks to bring a few hundredths to a tenth of an inch to northern Sonoma and Napa Counties with some coastal drizzle possible further south. Confidence remains low overall that the North Bay will experience any rainfall from this system due to guidance continuing to trending rain chances lower and lower across our CWA and shifting the rain further north. This system does look as though it will produce breezier conditions across the region with guidance showing widespread gusts to around 25 to 30 mph and locally stronger gusts across the elevated terrain.

AVIATION
(18Z TAFS)
Issued at 1158 AM PDT Sun Apr 20 2025

Stratus continues to clear this morning, with coastal communities and the North Bay Valleys taking the longest to dissipate. Expect VFR conditions at most sites within a few hours and then persisting into the early evening. Guidance shows another intrusion of the marine layer tonight, which will likely impact the coastal KSFO, KOAK, KHAF, KMRY, and KSNS with MVFR to IFR cigs possible. North Bay sites show a mix of stratus and mixed visibilities, though confidence is a touch lower on how low the vis could fall. Trended towards IFR cig and vis for these sites. Expect another round of clearing by mid to late tomorrow morning with any development.

Vicinity of SFO... Stratus has more or less cleared this morning, with only a few clouds hanging around. Expect VFR conditions to prevail through the evening, with uptick breezy west to west- northwesterly winds of 10-15kt possible. Winds should fall below 10kt before 06Z, with MVFR cigs returning during the early overnight hours. Leaned towards the persistence forecast, which should have MVFR cigs eroding just before or around 18Z.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Clear skies around much of the Monterey Bay region this morning, with VFR conditions likely prevailing through the early evening. Then MVFR to IFR cigs are expected overnight with skies clearing by mid to late morning tomorrow.

MARINE
(Today through Friday)
Issued at 927 AM PDT Sun Apr 20 2025

Breezy to gusty north/northwest winds are building in the northern waters along with building north swell. Winds look to increase and spread across the outer waters into the work week. The occionally near gale gusty northerly winds look to become more widespread into the mid week.

MTR WATCHES/WARNINGS/ADVISORIES

Tngt
SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm