textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 218 PM PDT Wed Aug 12 2026

- Near-critical fire weather conditions Wednesday afternoon through Thursday early morning across Monterey and San Benito Counties due to high based thunderstorms

- Up to a 15% chance for elevated rain showers/thunderstorms Wednesday across the Central Coast

- Cooling trend through Friday will bring well below normal temperatures, gradual warming trend this weekend into next week

- Minor coastal flooding for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay through Thursday morning

SHORT TERM

Issued at 218 PM PDT Wed Aug 12 2026 (This evening through Thursday night)

Isolated thunderstorm potential continues through this evening along the Central Coast with increasing confidence compared to this morning. Radar shows a line of storms developing off of the Big Sur coastline and moving in to Monterey County. As of this morning/early afternoon, we have cells moving inland in the vicinity of the Timber Fire which produced lightning both offshore and on land. This cell backbuilt to the southwest with additional cells developing in the wake of the original (inland) cell over the marine environment. These additional storms have been slowly moving inland in the vicnity of the Timber Fire and may also become favorable to produce lightning. Any of these cells will be capable of producing gusty, erratic wind and dry lightning with any rain evaporating before reaching the surface due to the elevated storm nature. Fuels are incredibly dry right now with near critical fire weather concerns across Monterey and San Benito Counties. If dry lightning occurs, it is likely to result in additional fire starts. Residents of interior Monterey and San Benito County (particularly along and within the higher terrain) should stay weather aware, avoid unnecessary activities that may result in sparks/fire, and follow guidance from local officials. Confidence is highest in thunderstorms over the elevated terrain with orographic lift acting as the trigger for storms to develop. This is an ongoing event and we will be paying close attention to the radar this afternoon and evening as it evolves.

Tonight into tomorrow, a low pressure system offshore will move into the Central Coast and bring additional chances for thunderstorms through Thursday morning. HRRR guidance shows several hundred joules/kg of MUCAPE moving across the Central Coast tonight into early Thursday with decent upper level support (700-500 mb lapse rates between 7-8 C/km) and lingering monsoonal moisture. Given that storms are currently occurring along Big Sur, it is likely that we will see additional storms again tonight through tomorrow morning across the Central Coast. Storms tonight and tomorrow morning could potentially reach as far north as the Santa Cruz Mountains and the South Bay. Storms are most likely to form along the higher terrain and be driven by orographic lift.

LONG TERM

Issued at 218 PM PDT Wed Aug 12 2026 (Friday through next Tuesday)

Thunderstorm chances diminish after Thursday with drier conditions to prevail into next week. Temperatures will remain well below normal across the Bay Area and Central Coast as upper level troughing persists through this weekend. This will keep highs in the 60s closer to the shoreline and in the 70s to mid 80s across the interior. The exception will be the interior Central Coast where highs will warm into the upper 80s to low 90s late weekend into early next week. Temperatures gradually warm next week as ridging pushes into the Desert Southwest from the Central US and troughing continues over the Eastern Pacific Ocean.

AVIATION

(18Z TAFS) Issued at 1112 AM PDT Wed Aug 12 2026

Another day, another marine layer. Stratus is making its way out of the remaining terminals and will retreat to the coastline for the rest of the day. VFR conditions will prevail through the afternoon. Onshore winds, generally from the southwest, become moderate (10-15 kt) this afternoon across the majority of TAF sites. Winds remain around 7-10 kt overnight with mid to upper level clouds passing overhead. A deeper marine layer will make a push inland tonight likely impacting all sites with medium confidence on the exact arrival. Relied on persistence in terms of timing for locations that have gotten a ceiling the past few nights. A mixed bag of IFR and MVFR ceilings are forecast across the region with medium confidence for STS to go LIFR. Ceilings are expected to clear late Thursday morning.

Vicinity of SFO...VFR with mid to high level clouds present. Onshore winds increase through the afternoon with the potential for occasional gusts up to 25-27 kt. SW winds remain breezy overnight with the marine layer expected to impact both OAK and SFO with MVFR ceilings shortly after midnight. Clouds are expected to scatter out later tomorrow morning, around 18-19Z.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Smoke and haze from the nearby fire will still be prevalent today. Currently monitoring the potential for lightning from high-based thunderstorms nearby the airports, though confidence is too low to include in the TAF. Will update and amend as needed throughout the day. Gusty SW winds are expected at MRY meanwhile SNS remains more NW with a lower chance for gusts. Stratus is expected to bring low-end MVFR ceilings to both terminals before sunset tonight and persist into late Thursday morning.

MARINE

(Today through Monday) Issued at 525 AM PDT Wed Aug 12 2026

Fresh to strong northwest winds will continue into early Thursday with for the northern outer waters. Isolated near gale gusts will continue through Wednesday morning. Seas will be rough and around 9 to 11 feet, with wave heights slowly subsiding through Thursday. Long period southerly swell will gradually increase late in the week, peaking between 16 to 18 seconds late Friday through early Sunday. Expect haze and smoke to limit visibility at times along the Big Sur coast due to the Timber fire.

FIRE WEATHER

Issued at 118 AM PDT Wed Aug 12 2026

Near-critical fire weather conditions Wednesday afternoon through Thursday early morning across Monterey and San Benito Counties due to high based thunderstorms. Confidence remains low for a low probability/high impact scenario of elevated rain showers/thunderstorms across the Central Coast from a low pressure system that is currently 300 miles southwest of Point Conception. Erratic/gusty outflow winds of 35-45 mph can be expected with any elevated rain showers/thunderstorms. Lightning will pose the risk for new fire starts and has the potential to hinder operations on the Timber Fire in Big Sur. The areas of most concern will be in the higher terrain above the marine layer (1,500 feet), namely the Santa Lucia Mountains and Gabilan Range. Poor minimum daytime relative humidity around 30% is expected in the afternoons with little-to-no recovery overnight.

Sarment

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 2 AM PDT Thursday for CAZ006-506- 508-529-530.

PZ...Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.