Marine Weather and Tide Forecast for Diablo Grande, CA

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
(00Z TAFS)
Issued at 657 PM PDT Sun Apr 20 2025

Stratus and fog /MVFR-IFR/ continues along the coast from the Carmel Highlands to the vicinity of Bodega Bay per satellite imagery. Drier air flow continues to advect southward over the northern coastal waters and midway southward along Sonoma County coastline. Recent HRRR output has followed this pattern fairly closely, showing additional clearing taking place through the evening to the south of Bodega Bay. Surface winds are forecast to become weakly cyclonic over the inner waters tonight and Monday morning, the wind field and radiational cooling aloft becoming a focus for regrowth of stratus and fog. Onshore winds will locally bring stratus and fog /MVFR-IFR/ inland. The marine layer depth has compressed to around 1200 feet per recent profiler data and spot checking coastal temperatures. A thinner marine layer will help speed up stratus and fog mix out times Monday morning.

Vicinity of SFO...VFR, then MVFR stratus ceiling forecast 09z early Monday, mixing out to VFR 17z Monday. West-northwest wind 15 to 25 knots until 04z this evening, decreasing to a light west wind then shifting to light northeast wind Monday morning. West-northwest wind resuming Monday afternoon with gusts near 20 knots until early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Satellite imagery shows stratus /MVFR-IFR/ filling in across the Monterey Bay. The marine layer depth at the Fort Ord profiler has recently varied between 1200 and 1400 feet.
HRRR output shows stratus and fog filling into the Salinas Valley tonight and Monday morning. Stratus and fog /MVFR-IFR/ mix out by around noon Monday. Onshore winds mainly continuing during the period between 5 and 15 knots.

MARINE
(Tonight through next Saturday)
Issued at 544 PM 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 gusty occasionally gale force northerly winds in the afternoon look to become more widespread into the mid week.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 PM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.