Issued at 858 PM PDT Thu Oct 15 2026
The Red Flag Warning for the North Bay Interior Mountains goes into effect at 10 PM this evening and will remain in effect through 11 AM Friday. Offshore winds are picking up across the highest peaks within the North Bay Interior Mountains with gusts reaching 30 to 50 mph. The strongest gusts will be confined to these highest elevations but moderate offshore winds are expected to mix into the rest of the zone by late tonight/early Friday. Humidity values are expected to drop as offshore winds strengthen with most locations seeing overnight humidity values between 15 to 25%. If a fire is able to develop it has the potential for rapid spreed given how critically dry conditions are. Near critical fire weather conditions continue across the higher elevations for the rest of the Bay Area through Friday morning.
, Issued at 132 PM PDT Thu Oct 15 2026 (This evening through Friday night)
Another warm and sunny day across our area with offshore flow providing above normal temperatures and abundant sunshine. With an upper level ridge over NorCal and upper level low over SoCal, we're seeing a common setup for a relatively weak Diablo wind event through the North Bay interior mountains, which has resulted in a Red Flag Warning issued for 10p tonight through 11am Friday for that area. The highest peaks around Mt St Helena have already seen gusts between 50-60 mph and we expect that to continue until winds at lower altitude begin to increase later tonight through late morning Friday. It hasn't rained in that part of the North Bay since September 4th, so conditions and fuels are very dry (see the Long Term discussion below for how that may change next week). Elevated fire weather concerns extend beyond the Red Flag Warning so we continue to message to abstain from any activities that could ignite a wildfire. The offshore flow continues to work against marine layer development with some of our coastal locations like Half Moon Bay and Monterey already in the low 80s and representing some of our highest temperatures of the day so far.
The offshore flow will continue tonight providing clear skies area wide. Thermal belting above 1000ft over much of our area will result in poor RH recovery and overnight lows well above normal, providing little relief from the heat until at Saturday night.
..issued at 132 PM PDT Thu Oct 15 2026 (Saturday through next Wednesday)
We expect the Red Flag warning over the North Bay interior mountains to expire at 11am Friday with easing winds as the mitigating factor, temperatures will remain warm with very dry conditions and fuels persisting through Saturday until a notable pattern change sets in on Sunday.
An upper level trough to our north will approach the coast over the weekend bringing a return of onshore flow, a subsequent cold front and notably cooler temperature and multiple days through the middle of next week with scattered light rain chances. We're not expecting any one location to see more than a 0.25", and most locations that see some rain will get less than a 0.10" but confidence is increasing that most of our area will see at least a little bit of rainfall, with exact timing still too far out to speak of with any confidence.
(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.
(tonight through next Wednesday) Issued at 934 PM PDT Thu Oct 15 2026
High pressure to the north will maintain gentle to moderate northerly breezes over the coastal waters through Friday. A storm passing well to the north will usher in moderate to fresh northerly breezes this weekend. The increasing winds will bring a fresh swell and steeper wind waves.
Ca, Red Flag Warning until 11 AM PDT Friday for CAZ504.
PZ, None.
