FXUS66 KMTR 190527 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1027 PM PDT Mon May 18 2026 ...New SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 1026 PM PDT Mon May 18 2026 - Diurnally driven winds, with onshore winds during the afternoon and early evening. - Above normal temperatures continue through midweek with seasonal temperatures returning late week && .SHORT TERM... Issued at 1026 PM PDT Mon May 18 2026 (Tonight through Tuesday) The forecast appears to be on track, with broad upper level troughing holding over much of the western U.S. while high pressure builds over the eastern Pacific. The good news, is that our breezy offshore winds have eased substantially leaving us with fairly calm weather in return. Tonight, skies will remain clear and temperatures will generally fall into the 50s for the valleys, perhaps upper 40s for some coastal sites and the southern Salinas Valley. At higher elevations, a thermal belt will exist as temperatures fall into the mid 50s to low 60s and may still have some northerly winds. For those in the valleys, winds will generally be light and variable. Tomorrow, another warm day will be on tap. The question will be, how do the temperatures pan out? Offshore flow won't be as prevalent, which means there could be less of a downsloping / warming of the air affect. But, that upper level high slowly creeps towards us and the marine layer is essentially negligible. Opted to blend a bit of the observations from Monday to the NBM giving us a similar forecast, to what occurred yesterday. The interior Bay Area valleys should make it into the 80s, perhaps near 90 degrees, while coastal communities experience a tighter gradient of highs in the 60s to low 70s. The San Francisco Peninsula should be similar, with the Pacific side having temps range from the mid 60s to low 70s, while the Bay side ranges from the upper 70s to mid 80s. And finally the Central Coast, interior locations rise into the mid 70s to mid 80s, while coastal communities vary from the mid 60s to the low 80s. && .LONG TERM... Issued at 1026 PM PDT Mon May 18 2026 (Tuesday night through next Monday) No major changes to the extended forecast. Upper level troughing looks to keep hold over the western US through at least Wednesday, with that Pacific high slowly peeking into northern CA. This should bring a return of onshore flow to the region and eventually the marine layer. Warm weather looks to linger through at least Wednesday, with Thursday potentially seeing a slight change in temperatures if the marine layer develops. Guidance for Thursday caps it at 500ft at best, with the marine layer getting to 1000ft by Friday. The marine layer appears to better establish itself Friday night into Saturday, likely getting to around 1000ft again. Will need to keep an eye on this as it will affect how temperatures pan out. && .AVIATION... (18Z TAFS) Issued at 1021 AM PDT Mon May 18 2026 Currently VFR at all terminals. High confidence in VFR and diurnal winds prevailing through the TAF period. Winds may become calm and/or light and variable overnight. Vicinity of SFO...Currently VFR with westerly flow. High confidence in VFR and diurnal winds prevailing through the TAF period. Westerly winds will continue to diminish with the potential to become calm and/or light and variable overnight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Currently VFR and calm at MRY and VFR with northerly flow at SNS. High confidence in VFR and diurnal winds prevailing through the TAF period. && .MARINE... (Tonight through next Sunday) Issued at 932 PM PDT Mon May 18 2026 Conditions will continue to improve tonight as northerly breezes continue to diminish. Rough seas will prevail in the outer waters with moderate seas in the inner waters. Hazardous conditions for small craft will persist through the week across the northern outer waters due to rough seas and strong northerly breezes. && .FIRE WEATHER... Issued at 1251 PM PDT Mon May 18 2026 Gusty north to northeast winds will continue through this afternoon before easing tonight into tomorrow. Peak gusts between 35 to 45 mph are still possible across the higher elevations into this evening. Daytime humidity retention remains poor with most sites staying around 10-25% across the interior and higher peaks with limited overnight recoveries. Winds ease by Tuesday but fire weather concerns will linger through late week as light offshore flow continues and daytime humidities remain poor. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Coastal Flood Advisory until 3 AM PDT Tuesday for CAZ506. PZ...Small Craft Advisory until 3 AM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 9 PM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 9 AM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...KR LONG TERM....KR AVIATION...Sarment MARINE...Sarment 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