
Wildfire smoke continues to impact air quality from the Great Lakes region into New England and the Mid-Atlantic today with widespread Air Quality Alerts in effect. Severe thunderstorms are expected across portions of the Ohio Valley and Lower Great Lakes into the Mid-Atlantic and Northeast, this afternoon into the evening. Monsoonal thunderstorms may bring areas of flooding to the Southwest. Read More >
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750 FXUS66 KMTR 182035 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 135 PM PDT Sat Jul 18 2026 ...New SHORT TERM, LONG TERM, FIRE WEATHER... .KEY MESSAGES... Updated at 120 PM PDT Sat Jul 18 2026 - Near or slightly below normal temperatures and higher humidity through the first half of the upcoming week. - The marine layer and mid to upper level cloud cover will continue to help keep temperatures cooler under building high pressure. && .SHORT TERM... Issued at 120 PM PDT Sat Jul 18 2026 (This evening through Sunday night) Stratus retreated back to the immediate coastline by late this morning. A few spots from Pacifica south to Monterey may only see partial clearing through mid-afternoon. A slightly stronger marine layer (~1500-2000ft) across the North Bay valleys has temperatures running 5-10 degrees cooler than this time yesterday, so have adjusted todays highs there about 3-5 degrees cooler from the NBM. The onset of a relatively normal diurnal intrusion of the marine layer this evening will occur with a similarly normal exit Sunday morning. Patchy coastal and valley fog is most likely across the North Bay with little to no impacts expected. A weak fetch of offshore flow/thermal belting at 925MB will keep overnight lows at higher elevations over the East Bay Hills and Santa Lucias well above normal with poor overnight RH recovery. Light winds will help mitigate fire weather concerns somewhat, but any ignition could spread quickly on steep slopes. && .LONG TERM... Issued at 120 PM PDT Sat Jul 18 2026 (Monday through next Friday) Temperatures will be near or below normal through the extended forecast with Tuesday being the warmest day of the week despite building high pressure. The marine layer influence, especially for the Bay Area and North Bay, will help to keep temperatures close to or below normal. Not much change to the expected push of monsoonal/tropical moisture from the south as Elida tracks north after becoming extratropical. PWATS near 2.0" and 150%-200% of normal are expected to peak Tuesday afternoon. Attm slight H50 height rises and anemic mid-level lapse rates less than 7C/km indicate a low probability of elevated convection (and dry lightning potential) developing. However, mid-level cloud cover spreading east from the remnants of Elida over the EPAC will further help to keep temperatures in check for the first half of the week, including Tuesday. && .AVIATION... (18Z TAFS) Issued at 1045 AM PDT Sat Jul 18 2026 Improving flight categories are forecast at all terminals with VFR anticipated at most terminals (except KHAF) in the next 1-2 hours. There is high confidence in this transpiring. MVFR to IFR is anticipated to return this evening and into the pre-dawn hours on Sunday. Confidence in the onset time is medium. Confidence in MVFR at SJC and LVK is relatively lower, compared to other terminals, but model consensus does favor at least a few hours of MVFR. There are chances for LIFR ceilings/visibility at SNS and APC, however, the depth of the marine layer may be sufficient to mitigate this threat. Trends will be monitored as the potential is non-zero. VFR will return late morning/early Sunday afternoon. Vicinity of SFO...VFR currently with MVFR returning this evening due to a marine layer push. East to variable winds at the start of the TAF period are anticipated to become more WNW`ly by 20Z today. Gusts as great as 25 knots are advertised with medium to high confidence. Confidence in the onset of MVFR cigs around 03Z Sunday is medium and there could be impacts to the evening push. Some model guidance advertises IFR ceilings, but confidence is not high enough to include in the TAF at this time. VFR is anticipated to return mid-morning Sunday. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR this afternoon with MVFR/IFR ceilings returning quickly, near or just after 00Z Sunday. There is some potential for IFR visibility, however, the threat seems too low to include in the TAF at this time. There`s a chance that VFR may return before the end of the current TAF period (17Z Sunday), but for now will opt for simplicity given the range in the TAF. && .MARINE... (Today through Thursday) Issued at 1045 AM PDT Sat Jul 18 2026 Moderate to fresh northwesterly breezes will prevail over the weekend, diminishing to become moderate by next week. Moderate seas will also prevail. Moderate southerly swell will increase from tropical cyclone activity across the eastern Pacific through next week. && .FIRE WEATHER... Issued at 120 PM PDT Sat Jul 18 2026 Cooler than normal temperatures with assistance from onshore flow and relatively normal diurnal intrusion of the marine layer will continue through the weekend into next week. RH recovery will be excellent for coastal areas and valleys, and moderate to good farther inland. However weak offshore flow/thermal belting will result in poor RH for higher elevations, especially above 1500- 2000ft across the East Bay Hills and Santa Lucias. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...JM LONG TERM....JM AVIATION...Bain MARINE...Bain Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea |
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| Yesterday | ⇛Visible ⇛Nighttime ⇛GeoColor+GLM | Today | |
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