Issued at 844 PM PDT Sun Mar 8 2026
After the brief dip in temperatures Monday and Tuesday, the warm weather returns by mid week. The pattern is different, however. The weekend warmth was mainly driven by offshore winds. These dry winds warm adiabatically as they move downslope and compress under the higher pressure at lower altitudes. Contrast that with the upcoming pattern that will be driven by a pure ridge in the long wave pattern. This still warms the air from adiabatic compression, but the sinking is large scale and doesn't rely on terrain or wind. This means lighter winds, clear skies and cool mornings. One important difference between the 2 types of warm patterns is the micro climates. Offshore winds bring warm and clear conditions all the way to the beach. Ridging allows a shallow marine layer to form and bring cooler, more humid conditions to low-lying coastal areas (think June Gloom).
The strength of this ridge is noteworthy. By next weekend, there is a 90% chance we set the daily record for 500 mb height, and a 50% chance we set the monthly record for all March soundings (nearly 5,000 observations going back to 1948). There's still some uncertainty as to what that means for surface temperatures. The NBM ensemble mean is roughly 5 degrees above the deterministic run by the end of the week. We'll likely be in the 80s across the interior next weekend.
, Issued at 132 PM PDT Sun Mar 8 2026 (Tonight through Monday)
High pressure aloft that has been nosing over our service area the last couple days is slowly weakening while retreating out to sea. This has allowed for weak upper ridge axis to establish just off the coast with a weak thermal trough surface reflection. This thermal trough will be fairly short lived, but is has allowed weak offshore flow to remain just a little longer than expected. As the afternoon ticks on the ridge will continue to retreat, eroding the offshore thermal trough. Heating across the land areas will generate another thermal through and help to induce onshore flow to develop. This has already begun in some areas. Onshore flow will impact all regions of our service area by early this evening. As a result, expect low clouds and some patchy fog to develop this evening and overnight. This marine layer should be about 1000-1500 feet in depth and should erode fairly quickly tomorrow morning as weak offshore winds at 925 mb develops for a short time. After the morning low clouds and fog erode, Monday will be another nice day, but on the cooler side. Relative to what we've had of course. Temperatures will drift towards climatology the next couple days. As part of this gentle pattern shift, we'll see a weak dry boundary (seen in OPC charts) come into the area on Monday. Given that high pressure remains anchored and stout over the Eastern Pacific, low pressure over us means a tightening pressure gradient over the coastal waters. In turn, this means increasing winds out of the Northwest for Monday. Look for breezy conditions along the coast and the coastal mountains through the day on Monday.
..issued at 132 PM PDT Sun Mar 8 2026 (Monday night through next Saturday)
Monday night will bring another night of low clouds and fog for the service area. Tuesday will be the closest we get to seasonal normal temperatures as a broad upper trough passes just North of the area. On the backside of the upper trough another upper ridge will build. Unlike the last one with a West <-> East orientation, the one building midweek will have a classic North-South ridge axis. This will bring rapidly warming temperatures to our entire area with the highest temperatures in East and South Bays and the Central Coast. While models are consistent with the warm up, the closer to water, the wider the spectrum of solutions. Inland locations have fairly tight spreads of probabilities. In general Wed-Fri, models have spread of temperature from the mid 70s to the upper 80s, depending on location. Temps should moderate next weekend as the ridge retreats slightly before building back stronger the week of the 15th. The next shot at any liquid water falling from the sky won't be until the last week of March and into April. By that point the odds of receiving beneficial amounts starts to plummet. As of Sat 7 Mar, our service is standing about 75-125% of normal on the water year, which began 1 Oct 2025.
(06z TAFS) Issued at 948 PM PDT Sun Mar 8 2026
Onshore winds have returned to the area, bringing cooler and more humid air to the coastal boundary layer. A narrow cloud deck is already impacting HAF, MRY and SNS. The big question tonight is if this cloud deck will expand to reach the busier Bay Area airports or not. The trend in guidance has been marginally better over my shift, but there is still nearly a 30% chance that the big 3 airports see ceilings around 13-17Z. If ceilings form, they will likely be IFR based on the current impacts along the coast.
Vicinity of SFO, The terminal is clear for now, with stronger than expected winds funneling through the San Bruno Gap. The surface humidity has responded to the shift from offshore to onshore winds this evening. At 3:20 PM the dew point depression was 27 degrees. Now its down to 3 degrees. That means stratus has the potential to surprise us and just form over the terminal, rather than advect in. Otherwise strong WNW winds are expected Monday afternoon after any low clouds clear.
Monterey Bay Terminals, While the Monterey Bay eddy hasn't developed yet, the southern half of the bay did fill with stratus as of 04Z, and ceilings are slowly working their way south. These impacts will persist through the night before gradually improving in the late morning Monday.
(tonight through next Saturday) Issued at 844 PM PDT Sun Mar 8 2026
Building high pressure over the Eastern Pacific will generate strong to near gale force northerly winds through Wednesday morning. These winds will build very rough seas of 12 to 15 feet in exposed waters. Conditions will improve somewhat later in the week, but will remain hazardous to small craft.
Ca, None. PZ, Small Craft Advisory from 3 PM to 9 PM PDT Monday for Mry Bay.
Small Craft Advisory until 3 PM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory from 9 AM Monday to 3 PM PDT Tuesday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.
Gale Warning until 3 PM PDT Tuesday for Pt Arena to Pt Reyes 10- 60 NM.
Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM.
Gale Warning from 3 AM Monday to 9 AM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM.
