Marine Weather and Tide Forecast for Greenfield, CA

SHORT TERM
Issued at 1201 AM PDT Fri Apr 17 2026 (Today and tonight)

Offshore flow produced gusty winds across our area today, but especially higher elevations of the North Bay and East Bay Hills.
The highest measured wind gust was at Mt St Helena (~4400ft) shortly after 3pm at 63mph, but is still gusting at 57mph late tonight. The fetch of offshore flow will persist overnight through mid-morning Friday as the upper trough responsible continues moving east.
Overnight lows from the East Bay Hills south through San Benito and Monterey County will be chilly, especially at higher elevations, where winds aloft are weaker and more efficient radiational cooling will occur under clear skies. Morning winds will gradually ease by the afternoon as progressive ridging approaches the West Coast.
Temperatures will jump about 5 degrees inland, and remain similar to yesterday along the coast as weak onshore flow is reestablished.

LONG TERM
Issued at 1201 AM PDT Fri Apr 17 2026 (Saturday through Thursday)

Overnight lows tonight into Saturday morning will shift closer to normal as the progressive upper ridge moves across our area and gradually amplifies as it moves east. Temperatures will be in the mid-70s to near 80 inland, once again not much increase along the coast with onshore flow. Deterministic guidance is still struggling with the evolution and timing of the developing offshore disturbance. Sunday now looks dry and relatively pleasant, just slightly cooler as cloud cover increases out ahead of the upper low.
The North Bay is likely to receive rainfall Monday, however there is plenty of uncertainty for the remainder of our area wrt to the initial ave ejecting east onshore. Tuesday has the best chance for scattered showers and possible thunderstorms, especially if the trough becomes negatively tilted by Tuesday morning. Scattered showers may linger into Wednesday, with no clear signal for what the pattern looks like beyond the extended forecast.

AVIATION
(06Z TAFS)
Issued at 1009 PM PDT Thu Apr 16 2026

VFR is expected to prevail through the forecast period. Enhanced offshore flow aloft is producing LLWS out of the northeast for the North Bay terminals and farther south into KOAK.

Vicinity of SFO...VFR is expected to prevail through the forecast period. Expect northeast LLWS aloft through the overnight into Friday morning, especially at KOAK.

SFO Bridge Approach...Similar as SFO.

Monterey Bay Terminals...Expect VFR through the TAF period with offshore flow overnight, returning back to onshore by late morning.

MARINE
(Tonight through next Wednesday)
Issued at 1009 PM PDT Thu Apr 16 2026

Gale force winds have eased over our northern outer waters this evening. Strong winds will persist through Friday morning with hazardous conditions persisting across our outer waters and continued choppy conditions for inner waters and bays. Winds will ease further by Friday afternoon into Saturday with seas gradually subsiding.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 3 AM PDT early this morning for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.