094 FXUS66 KMTR 091823 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1123 AM PDT Wed Jul 9 2025 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 101 AM PDT Wed Jul 9 2025 - Warming trend begins today through the weekend, with patchy Moderate HeatRisk across the Bay Area and Central Coast Thursday and Friday. - Localized elevated fire weather threat starting today through the weekend across the higher elevations. && .SHORT TERM... Issued at 101 AM PDT Wed Jul 9 2025 (Today and tonight) Satellite imagery shows widespread marine layer stratus across the valleys of the Bay Area and Central Coast, as data from the Fort Ord profiler shows the top of the marine layer becoming more diffuse while rising to at least 3000 feet over the last evening. Low temperatures this morning will hover in the lower to middle 50s in the lower elevations, and as high as the lower 60s in the highest peaks. Today marks a pattern change from the cooler regime of the last few days to a warming pattern that (spoiler alert) looks to set up for the rest of the week. The upper level low that brought us the robust marine layer and the cool temperatures is dissipating while it meanders towards landfall in the North Coast. This will allow an ridge that`s set up over the desert Southwest to edge into the state while a synoptic high pressure system develops in the east Pacific, causing temperatures to warm. Temperatures will range from the upper 70s to the middle 80s inland, with the warmest spots in southern Monterey and San Benito Counties reaching the upper 90s, while locations on the Bays reach highs in the upper 60s and the 70s. The marine layer will compress, but the coastal areas should remain rather cool with highs in the upper 50s to the lower 60s. Some elevated fire weather threat is forecast to develop today across areas above and inland of the marine layer`s influence. The combination of dry daytime humidities of around 15-30% and localized gusts to 30 mp will be the main factors behind the elevated threat. However, the winds will remain onshore, leading to the fire weather threat being diurnally driven, especially in the foothills where lighter winds and good overnight recoveries are expected each night. && .LONG TERM... Issued at 101 AM PDT Wed Jul 9 2025 (Thursday through Tuesday) Temperatures continue to rise on Thursday and Friday as the high pressure systems become more established, with the inland valleys seeing highs in the middle 80s to middle 90s on both days, while the warmest interior locations see temperatures rising up to a few degrees above 100. Patches of Moderate HeatRisk are expected on Thursday and Friday across the interior North Bay, East Bay, and South Bay, in addition to the Santa Lucia mountains and the southern tip of San Benito County. Remember to take frequent cooling breaks and drink plenty of water if participating in outdoor activities on both days. As a very weak upper level disturbance passes through the state this weekend, temperatures will cool slightly to the lower 80s to lower 90s in the interior Bay Area with an shortwave trough coming through the West Coast, while the interior Central Coast remains rather warm with temperatures in the 90s. The pattern will otherwise remain rather stable through the early part of next week, with warm inland temperatures, cool coastal temperatures, light onshore winds, and localized elevated fire weather threat in the interior developing each afternoon. && .AVIATION... (18Z TAFS) Issued at 1108 AM PDT Wed Jul 9 2025 The ceilings are clearing out with mostly clear skies expected through the afternoon. The exception is along the immediate coast, where IFR-MVFR conditions are possible through the day. There is a pattern shift ongoing today as high pressure becomes the dominant feature and compresses the marine layer. This will cause less expansive stratus coverage Thursday morning. On the other hand ceilings and visibility will be lower for the terminals that are close enough to the coast to remain in the marine layer. Vicinity of SFO...The ceiling scattered out just before 18Z, and VFR conditions are virtually guaranteed for the next several hours. The uncertainty starts to increase around 03Z. The persistence forecast would bring MVFR ceilings back at this time, lowering to IFR later in the night. However, as the marine layer compresses, the stratus won`t push inland as fast. With NW winds in the boundary layer, it`s likely that the Peninsula hills will help protect the terminal from an early ceiling return. By 12Z Thursday morning, there is a 50-60% chance that SFO will develop a ceiling. If so, the height will be close to the MVRF/IFR threshold. In summary, the ceiling timing and height confidence is low beyond the first 9 hours of the TAF. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals...With a compressing marine layer, MRY will spend much longer under a ceiling than SNS over the next couple days. With NW winds there is also a good chance for LIFR ceilings and possibly fog development in the early morning. && .MARINE... (Today through Monday) Issued at 1108 AM PDT Wed Jul 9 2025 As the gradient between high pressure in the East Pacific and lower pressure over the Intermountain West increases, fresh to strong NW winds will develop through the afternoon and evening. These winds will maintain strength through Thursday, building rough seas in the exposed waters. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 3 PM to 9 PM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 3 PM this afternoon to 9 PM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...DialH LONG TERM....DialH AVIATION...Flynn MARINE...Flynn 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