Issued at 932 AM PDT Sat Jul 19 2025
Pretty widespread stratus coverage continues across much of the Bay Area and Central Coast. Overcast skies should clear across the interior by late this morning and patchy clearing is expected along the coastline this afternoon. Highs in the upper 70s to low 90s across the interior with the interior Central Coast reaching the upper 90s today. Still monitoring the potential for strong winds Sunday and Monday along the coast, mountain ridgetops, and gaps/passes. Otherwise, no changes to the overall forecast.
, Issued at 247 AM PDT Sat Jul 19 2025 (Today and tonight)
Another night shift and another round of marine layer stratus. Despite similar sensible weather there are some minor differences. The best way to describe the longwave pattern over the forecast area is the "high pressure squeeze play". A few upper level lows (SW British Columbia, well offshore of NorCal, and SoCal/Baja border) all surround an area of high pressure overhead. The "squeezed" high pressure didn't completely erase the marine layer, but definitely compressed it. Pt Sur and Bodega Bay profilers are reporting a marine layer depth near 1200-1500 feet. The compression of the marine layer is reflected with lower CIG heights at area airports, spotter reports of fog, drizzle/bucket tips, and webcams showing fog.
Despite a cloudy start to the weekend inland sunshine is expected with coastal clouds by this afternoon. A similar sight that we've been seeing the past few days. That being said, the high pressure overhead will lead to slightly warmer temperatures today, especially away from the coast. Highs will generally be in the 60s/mid 70s coast/bays and 70s to lower 90s inland, locally upper 90s interior Central Coast. Despite the warm up these forecasted highs are still below normal for late July.
Saturday night into Sunday morning will feature another marine layer push, but on the compressed.
Elevated fire weather concerns remain above the marine layer. We're pushing nearly a week of little to no relief for the high elevation regarding humidity recovery. Current obs shows RH below 20% for some of the higher peaks.
..issued at 328 AM PDT Sat Jul 19 2025 (Sunday through Friday)
Longwave pattern shift to kick off the long term. The "high pressure squeeze play" quickly comes to an end as the high gets pushed southward. The upper level low over SW BC and its associated trough deepens over the PacNW and NorCal, which helps with the southward push of the high pressure. The deepening trough will end any warm up and deepen the marine layer. Subtle cooling will be seen on Sunday with more widespread cooling on Monday into next week. The upper trough will also lead to increasing northerly flow. The increase in wind has been advertised by the models for several days now and the 00Z run is no different. Strongest winds will be Sunday night lingering into Monday afternoon/evening over the coastal waters, higher peaks, inland gaps/passes. While not strong enough to warrant a wind advisory there will be a 6-8 hr window with some solid wind, especially the East Bay passes. Goes without saying, but the winds will increase fire weather concerns too. Winds will finally ease late Monday night.
Cool and relatively quiet weather continues toward the end of the month.
(18z TAFS) Issued at 1043 AM PDT Sat Jul 19 2025
IFR at coastal sites and North Bay sites this morning while MVFR persist across the Bay Area terminals. Conditions will return to VFR by around 18Z-20Z this afternoon for most inland TAF, with the exception of HAF where IFR/MVFR conditions look to persist through much of the TAF period. Onshore winds increase this afternoon before easing after sunset. Rather high confidence for MVFR conditions to return this evening before lowering to IFR by late evening and into Sunday morning. The greatest potential for LIFR conditions will be across the North Bay and Monterey Bay terminals early Sunday morning before ceilings begin to lift by late morning. Ceilings clear out by 18Z-20Z for most coastal sites with earlier clearing across the interior TAF sites. Onshore winds increase once again by Sunday afternoon.
Vicinity of SFO, IFR currently but are forecast to lift to MVFR before clearing between 18Z-20Z. Onshore winds increase this afternoon before easing after sunset. High confidence for MVFR ceilings to return this evening before lowering to IFR either late tonight or early Sunday morning. Conditions return to VFR by 18Z-20Z Sunday with an increase in onshore winds by Sunday afternoon.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, IFR currently but are forecast to lift to MVFR. Low ceilings will scatter out by 1930Z-2100Z with an increase in onshore winds this afternoon. High confidence for early return of MVFR ceiling this evening before lowering to IFR late this evening or early Sunday morning. Greatest probability for LIFR conditions early Sunday morning at MRY.
(today through Thursday) Issued at 932 AM PDT Sat Jul 19 2025
Light to moderate northwesterly breezes will continue across much of the coastal waters through Saturday night. Gusty winds, potentially hazardous to small craft, also develop each afternoon and evening through the Golden Gate and into the Delta. Winds will increase slightly on Sunday before easing into next week. Slight to moderate seas persist through the remainder of the forecast period.
Ca, None. PZ, Small Craft Advisory until 9 PM PDT this evening for SF Bay N of Bay Bridge.
Small Craft Advisory from 9 AM to 9 PM PDT Sunday for SF Bay N of Bay Bridge.
Small Craft Advisory from 3 PM this afternoon to 9 PM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM.
