textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1201 AM PDT Fri Apr 17 2026

- Periods of gusty offshore winds, especially at higher elevations, continue through early this morning

- Seasonably warm temperatures expected today through the weekend

- Cooler temperatures and beneficial rain for the beginning of next week

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

(12Z TAFS) Issued at 505 AM PDT Fri Apr 17 2026

Offshore winds and a deeply dry air (continental air) intrusion support VFR for the 12z TAFs. Gusty offshore winds in the hills and mountains will gradually subside through morning, resulting in a decrease in low level wind shear. Currently the ACV-SFO and UKI-STS pressure gradients are 5.2 mb and 2.2 mb respectively. The WMC-SFO pressure gradient is 9.6 mb. These gradients are forecast to weaken later today and tonight with at least locally onshore winds returning during this time. Model forecasts show a few patchy coastal low clouds possible while high clouds move in tonight and Saturday.

Vicinity of SFO...VFR. North wind 10 to 15 knots shifting to northeast at times later this morning while also decreasing, however timing the decrease in wind is a low confidence forecast. It's very cold over the Great Basin, offshore winds are well entrenched at this time. Cold, dense basin air has steepened the WMC-SFO pressure gradient to 9.4 mb. The large scale pattern is progressive, this should help flip the surface wind to onshore in the afternoon. Westerly wind steadily decreasing to less than 10 knots tonight and Saturday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Dry air supports radiative cooling and chilly, denser air drainage winds through daybreak then steadily easing through morning. As mentioned for SFO the large scale pattern is progressive and this should help flip surface winds to onshore in the afternoon for the Monterey Bay terminals as well. Light and variable winds shifting to light southeasterly tonight and Saturday morning.

MARINE

(Today through Wednesday) Issued at 422 AM PDT Fri Apr 17 2026

Northwest winds and seas will gradually subside today through Saturday. On Sunday winds will shift to southerly ahead of a Pacific low pressure system that will bring rain to the area beginning early next week.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.