Marine Weather and Tide Forecast for Diablo Grande, CA

SHORT TERM
Issued at 1136 PM PDT Sun Apr 12 2026 (Tonight through Tuesday)

The coverage in light shower activity continues to gradually shift south late tonight into early Monday morning. Earlier this evening the KOAK sounding reported a 23.0C temperature at H50 which is in the 10th percentile for this time of the year. That cold core aloft helped support continued light shower activity after sunset from the SF peninsula south to Monterey Bay. The upper low will become more unorganized as it moves farther inland, evolving into a positively tilted upper trough extending from the Great Basin southwest into SoCal today. Lingering offshore scattered light showers will occasionally drift into the Big Sur coastline through mid-morning today with maybe a trace to a few hundredths of rain. Mondays highs at lower elevations will run around 5F-10F degrees below normal, with higher elevations 10F-20F degrees below normal. Cooler than normal temperatures persist tonight into early Tuesday, especially farther inland with cooler than normal air aloft persisting much of the work week.

LONG TERM
Issued at 1136 PM PDT Sun Apr 12 2026 (Tuesday night through next Sunday)

A progressive shortwave pattern sets in Tuesday through Thursday behind the exiting trough defining the term 'gradual warming' with most locations seeing an increase of 1 or 2 degrees each day through the middle of the week. A developing trough shifts south from the Pacific Northwest on Wednesday. There is a slight chance for rainfall across the North Bay Wednesday afternoon as the trough axis pivots east and south, but any rainfall will be measured in hundredths of inches with no impacts. Gusty winds will develop on the backside of the exiting trough later Wednesday through Thursday and into the early morning hours of Friday. However, updated deterministic guidance has shifted the disturbance farther east than this time last night with less of an 'inside slider' signal.
Winds will still be gusty at times especially at higher elevations but impacts seem low. There is also a signal for the potential of another round of rainfall toward the end of next weekend into the beginning of next week.

AVIATION
(06Z TAFS)
Issued at 959 PM PDT Sun Apr 12 2026

Isolated showers persist across the region through Monday morning with MVFR-VFR conditions possible within the showers. Otherwise, generally VFR through Monday afternoon. Light to gentle winds continue overnight with moderate onshore flow will developing in the afternoon. There is a low confidence (around 10-20% probability) of fog developing in the interior valleys tonight due to the recent rainfall. Confidence is too low to put this in the TAFs at this time. Monitoring the potential for MVFR-IFR stratus to develop Monday evening, potentially impacting immediate coastal and interior valley terminals.

Vicinity of SFO... Periodic shower activity continues through Monday morning, with generally VFR conditions expect when showers pass over the terminal. Light winds persist overnight before northwesterly flow develops Monday afternoon.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Isolated showers across the region through Monday morning, otherwise VFR through Monday afternoon. Light drainage flow continues overnight before moderate northwest winds develop for Monday afternoon. Monitoring the potential for IFR-MVFR stratus to develop along the northern edge of the Santa Lucia and Gabilan ranges on Monday evening, with potential side impacts to the terminals.

MARINE
(Tonight through next Saturday)
Issued at 959 PM PDT Sun Apr 12 2026

Isolated showers persist into early Monday morning. Gentle northwest winds are expected to prevail tonight through Monday morning, increasing to a moderate to fresh breeze through Wednesday and a strong breeze to near gale force by Thursday.
Moderate seas continue through Wednesday before rough seas arrive on Thursday.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...None.