, Issued at 1223 AM PDT Sat Apr 18 2026 (Today and tonight)
A progressive upper level ridge axis will shift east across our area this morning, while temperatures inland climb into the upper 70s to low 80s. Locations most likely to reach or exceed 80 will be in the interior valleys of the South Bay and Central Coast where there will be plenty of sunshine and light winds. Coastal locations will be only slightly warmer than Friday with weak onshore flow during the day out ahead of the developing offshore disturbance. Even with the ridge exiting to the east, overnight lows into Sunday will be more mild than we've seen the last few nights with increasing mid/high level cloud cover insulating some of todays heat.
..issued at 1223 AM PDT Sat Apr 18 2026 (Sunday through Friday)
Sunday will be a nice transition day as the pattern changes for the first half of next week. Overall, consensus is improving but the timing of the first ejecting wave of the developing upper low is still in question. What we do know is that deep onshore flow will at least bring a return of stratus along our entire Pacific Coast Sunday night. Our official forecast has slight chance PoPs over the North Bay late Sunday evening but any rainfall initially would be measured in the hundredths. By sunrise Monday morning we may see more impactful rain over the North Bay coastal ranges then shift into the interior valleys. The slow moving system with notable longitudinal orientation out ahead initially will see areas of showers training over the North Bay. The WPC does have much of Sonoma County in a Day 4 Excessive Rain Outlook on Monday. The second wave approaches the coast overnight Monday into Tuesday as the associated trough becomes negatively tilted providing added lift and increasing baroclinic instability by late morning/early afternoon for any showers/storms moving onshore. The system will be slow to move onshore initially, but once inland it will eject east quickly. Attm, the pattern indicates another disturbance splitting off the back side with an inside slider trajectory for the second half of next week.
(12z TAFS) Issued at 439 AM PDT Sat Apr 18 2026
It's VFR except for patchy low clouds and fog /IFR-LIFR/. VFR prevails today with diurnal mixing then a few areas of low clouds and fog /IFR-LIFR/ redevelop tonight and Sunday morning.
Vicinity of SFO, VFR. Light and variable wind, possibly becoming light northeast this morning. Currently there is a 0.4 mb OAK-SFO pressure gradient. Otherwise a west wind redevelops by 21z and increases to 15 to 20 knots. West wind 10 knots tonight becoming a light west wind Sunday morning.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR today, then a few areas of coastal low clouds and fog /IFR-LIFR/ develop tonight and Sunday morning. Southeast cool air drainage winds 5 to 10 knots this morning becoming west to northwest 10 to 15 knots by noon or early afternoon. West wind 5 to 10 knots diminishing to light and variable winds tonight and Sunday morning.
(today through Thursday) Issued at 428 AM PDT Sat Apr 18 2026
Northwest winds will continue to diminish today. Winds shift to southerly Sunday ahead of an incoming low pressure system and cold front. Winds will strengthen ahead of the cold front Monday through Tuesday with localized strong gusts expected. Expect moderate seas, rain and a slight chance to chance of thunderstorms Monday night and Tuesday.
Ca, None. PZ, None.
