Marine Weather and Tide Forecast for San Francisco, CA

SHORT TERM
Issued at 1201 AM PDT Fri Oct 16 2026 (Today and tonight)

A Red Flag Warning remains in effect through 11 AM Friday for the North Bay Interior Mountains due to moderate offshore winds and critically dry conditions overnight. Minimal to no overnight humidity recovery is expected with humidity values between 15 to 25% expected. Winds across the North Bay Interior Mountains have picked up across the highest peaks and will spread into the remainder of the NB Interior Mountains tonight. Offshore gusts are expected to peak between 20 to 30 mph with stronger gusts possible across the highest ridgelines. Gusts between 40 to 60 mph have been observed across the highest peaks (3500+ ft) in northern Sonoma and Napa counties. As offshore winds pick up across the rest of the NB Interior Mountains, humidity values will drop with rapid fire spread possible should a fire start. Winds are expected to decrease by late morning with the Red Flag Warning set to expire at 11 AM. Although the winds will have decreased, very dry conditions (RH 10-20%) will persist through the rest of the day with poor overnight recoveries expected Friday into Saturday. As such, near critical fire weather conditions will continue across the higher elevations of the Bay Area and Central Coast through Saturday. If you are participating in any activity involving flames outdoors, be very careful and do not allow sparks/embers to escape. Listen to all guidance from local officials.

Upper level ridging continues with widespread above normal temperatures and Moderate HeatRisk peaking today. Minimal relief is expected along the coast due to upper level ridging mixing out the marine layer. Interior highs peak in the upper 80s to low 90s with coastal highs in the 70s to low 80s. Portions of the Santa Cruz Mountains and the southern Santa Clara Valley may reach the upper 90s. Expect hot conditions and patchy Moderate HeatRisk to continue into Saturday although a few degrees cooler than on Friday. If you're not a fan of hot weather, you're in luck as a pattern change is expected Sunday into next week (see Long Term discussion).

LONG TERM
Issued at 1201 AM PDT Fri Oct 16 2026 (Saturday through Thursday)

Temperatures return to more seasonal temperatures by Sunday as upper level ridging is replaced by broad troughing. High temperatures cool into the 70s to low 80s across the interior while the coast drops back into the 50s to 60s thanks to the return of the marine layer.
Upper level troughing impacts become more pronounced over the course of the next week as a deep upper level low becomes cut-off from the jet stream and lingers along the Central/Southern California coastline through late next week. At the same time, a surface low pressure system originating from the Gulf of Alaska will move southwards along the California coast next week. This system will bring a much cooler airmass into the region and see a return of fall temperatures in the 60s to 70s and morning lows in the 40s to low 50s. Recent guidance has trended towards the low staying offshore rather than moving onshore next week. The current forecast shows the highest rain totals along the Santa Lucia Range and Santa Cruz Mountains where totals are between a quarter to half an inch. For the lower elevations expect up to a tenth of an inch across the Bay Area and up to a quarter of an inch across the Central Coast.
Periods of gusty onshore winds are likely along the coast, the higher elevations, and across mountain gaps/passes next week. Winds don't look to be widespread enough to necessitate a Wind Advisory but favored windy locations (Altamont Pass) will definitely be gusty. Another item to watch is the potential for thunderstorms with this system. NBM guidance has consistently maintained a low chance (<15%) of thunderstorms across the region. In favor of thunderstorms is the fact that this is a cold core low which is bringing in cooler air and may be more favorable for ice crystal development/eventual lightning development. Anti-thunderstorm development is the new more offshore track of the low which keeps the best MUCAPE and CAPE values offshore. This may be a setup where we see some sort of convective activity over the marine environment but it doesn't make it onto land (if the current track holds).

Bottom line: expect a pattern change to occur next week with below normal temperatures, potential for light rain, breezy to gusty onshore winds, and a low potential for thunderstorms.

AVIATION
(06Z TAFS)
Issued at 950 PM PDT Thu Oct 15 2026

Not much change from previous TAF package...VFR through the forecast period due to offshore flow and dry air. Biggest challenge aviation wise will be dialing the winds. At points winds will be relatively light and variable. Offshore flow will strongest over the N and E Bays. Didn't include in the TAF for STS/OAK, but marginal (20-30% chc) of LLWS. LLWS most likely from 08-15Z.

One new item for the 06Z will be monitoring winds for KHAF early tomorrow. In these offshore flow set ups winds can sometimes align for the E to NE and increase as they surface toward the ocean.

Vicinity of SFO...VFR. Offshore push for the Friday AM rush.
Onshore heading into the Friday afternoon rush.

SFO Bridge Approach...VFR.

Monterey Bay Terminals...VFR.

MARINE
(Today through Wednesday)
Issued at 258 AM PDT Fri Oct 16 2026

Gentle to moderate northerly breezes will prevail over the coastal waters today and become moderate to fresh on Saturday.
These winds hold into the early portion of the week. The increasing winds will bring a fresh swell and steeper wind waves.

FIRE WEATHER
Issued at 132 PM PDT Thu Oct 15 2026

A Red Flag Warning was issued for the North Bay Interior Mountains that goes into effect at 10PM tonight and runs through 11AM Friday morning. This is due to moderate offshore winds very dry with very poor overnight humidity recoveries only reaching 15 to 25 percent. Rapid fire spread is possible given the combination of gusty northerly winds and very dry overnight conditions.

Elsewhere in the Bay Area, elevated to near critical fire weather conditions continue for the higher elevations late tonight through Friday morning. Dry conditions, poor overnight RH recovery, combined with the breezy winds, warmer weather, and available fuels leads to the elevated to near critical fire weather conditions.

MTR WATCHES/WARNINGS/ADVISORIES
CA...Red Flag Warning until 11 AM PDT this morning for CAZ504.

PZ...None.