Marine Weather and Tide Forecast for Cupertino, CA

SHORT TERM
(Today and tonight)
Issued at 250 AM PDT Fri May 16 2025

Another quintessential California day on the docket with mostly clear skies and breezy northwest flow. A quick check of the nighttime satellite shows some upper level cloudiness moving through the region associated with a subtle shortwave trough. This will likely lend a hand to some elevated cloud layers through this afternoon, but shouldn't cause any concern.

LONG TERM
(Saturday through Thursday)
Issued at 250 AM PDT Fri May 16 2025

By late Friday night we will start to see the impacts of a potent system progged to dig into the Great Basin. Gusty NW winds are expected to develop by midday Saturday lasting through Sunday evening. Confidence in the overall pattern is high as ensemble guidance has largely held steady for the past few days. One big change this morning, however. The latest guidance depicts a more open wave, which would ultimately lead to the upper low ejecting out into the Central Plains a bit earlier than previously expected. Where previous forecasts called for offshore winds through Monday morning, this morning's forecast package advertises less of an offshore wind component. Still looking at gusty N/NW winds early Monday morning, which will result in downsloping winds in the higher terrain of the interior North Bay. This will still lead to elevated fire danger for these areas through Monday where humidities will be low due to compressional heating and continental airmass influence. All in all, winds look to gust into the 30-40 mph range across inland areas and 40-50 mph along the coast and favored NW-SE oriented valleys and gaps. A longwave ridge pattern is restored by the middle of next week, promoting a drying trend and high temps warmer than seasonal normals.

AVIATION
(18Z TAFS)
Issued at 1055 AM PDT Fri May 16 2025

It's VFR except for a lingering patch of stratus over the Monterey Bay. VFR prevailing today with VFR extending into the evening, otherwise increasing coastal stratus and patchy fog /IFR-MVFR/ tonight and Saturday morning with patchy light coastal drizzle possible. Gusty northwest winds aloft resulting in low level wind shear over KSTS Airport 12z-17z Saturday morning.

Vicinity of SFO...VFR. Light northeast wind until early afternoon then shifting to westerly and increasing with gusts near 30 knots during the afternoon and evening. Gusty westerly wind tonight and Saturday.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals.. MVFR-VFR improving to VFR by early afternoon under diurnal surface warming and mixing winds. MVFR due to coastal stratus developing tonight, a few patches of light drizzle are possible as well. MVFR Saturday morning. Onshore winds 5 to 15 knots, strongest during the afternoon and early evening.

MARINE
(Today through Wednesday)
Issued at 1045 AM PDT Fri May 16 2025

Gusty to strong northwest winds will continue over the coastal waters today through the weekend, including much of early to mid next week. Hazardous marine conditions with rough to very rough seas will continue through Tuesday night.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 PM PDT Saturday for Mry Bay-SF Bay N of Bay Bridge.

Gale Warning until 3 PM PDT Saturday for Pt Arena to Pt Reyes 0- 10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0- 10 nm.

Small Craft Advisory until 3 PM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Gale Warning until 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM.