, Issued at 1038 AM PDT Tue Apr 7 2026 (This afternoon through Wednesday)
The weather is mostly quiet in the short term. The marine layer deepened to 2,200 feet according to the 12Z sounding. That was enough to bring stratus to the coast and bay adjacent valleys. Those clouds are now clearing, and the cooler humid air will retreat back to the immediate coast this afternoon. Temperatures today will climb into the 70s across the interior, while the coast is stuck in the low to mid 60s. A building short wave ridge will cause a subtle pattern shift through Wednesday. The most obvious impact will be some compression of the marine layer under the higher pressure. This will cause less extensive stratus coverage Wednesday morning compared to what we saw this morning. Otherwise conditions will be very similar to today with a gentle NW breeze, comfortable temperatures, and mostly clear skies in the afternoon.
..issued at 1038 AM PDT Tue Apr 7 2026 (Wednesday night through next Monday)
The pattern starts to change on Thursday. A mature, vertically stacked, cut-off low pressure system over the Eastern Pacific will slowly drift East towards the coast through the day. The first indications of this system will be increasing high clouds and a wind shift from NW to SW. The North Bay may get some light prefrontal rain in the afternoon or evening, and it's possible that an outer rain band could bring a lightning strike or two, but for most it will be a nice day. As the low continues to drift towards the coast, rain will become more widespread Friday morning and continue, off- and- on, through the day. The biggest question of the forecast is thunderstorm chances. Cut-off lows making landfall have surprised us in the past, so it's certainly worth a deep investigation as we get closer to the event. Since there is no obvious steering mechanism, it's hard to pin down what path these cut-off lows will take. That's important as the maximum lift, wind shear, and vorticity will all line up right near the low pressure center. The timing also plays a role, with maximum instability during the warmest temperatures in the afternoon.
The thunderstorm chances are revitalized Friday as a reinforcing trough digs down from the Gulf of Alaska. Whether we get storms or not remains in question, but an associated cold front will more than likely bring additional rain to the region. Right now the afternoon looks like the wettest period, but that could still change. All told we expect to get somewhere between 0.25-0.75" across the valleys, and up to 1.5" in the coastal mountains. From a rainfall perspective, that puts this event firmly in the beneficial category, with no flooding impacts expected. The only caveat is if thunderstorms or strong showers do develop, the storm motion will likely be relatively slow, so any associated downpours could cause localized flooding, especially in urban areas. A drying trend will probably start on Sunday, but the ensemble clusters disagree on the pattern next week. There's currently a 60% chance for a warm dry ridge, and a 40% chance for a cool, wet trough.
(18z TAFS) Issued at 1038 AM PDT Tue Apr 7 2026
The marine layer stratus has cleared across all terminals, including Half Moon Bay this time. The stratus bank has mostly pulled well offshore, increasing the confidence that it won't be back for an early return. That being said, there is still a very good chance for stratus to return overnight, but a compressing marine layer will limit the areal extent compared to yesterday.
Vicinity of SFO, Moderate to strong WNW winds are expected to develop by the early afternoon and persist through the evening before slowly tapering off overnight. There is about a 40% chance for stratus to return to the terminal Wednesday morning. The chances are very good that a cloud filled marine layer makes it to the coast and spills through the Golden Gate, but the wind direction and compressing marine layer both suggest SFO itself may stay in a clear pocket this time. If ceilings do develop, expect high IFR or low MVFR heights.
SFO Bridge Approach, Clear this afternoon. Similar to SFO Wednesday.
Monterey Bay Terminals, The skies have cleared and VFR conditions will remain through the day. The exact timing of the stratus return is hard to pin down. While I was surprised by how early the clouds returned last night, the marine layer is compressing and the clouds have pulled back well off the coast. GFSLAMP probabilistic guidance shows there is only a 20% chance of ceilings before 06Z tonight. They are, however, very likely to be in place by 12Z, with high IFR or low MVFR bases.
(today through Sunday) Issued at 1038 AM PDT Tue Apr 7 2026
A gentle to moderate NW breeze and slight to moderate seas will prevail through Tuesday. Winds will remain moderate while gradually shifting to a SW direction from Wednesday through Thursday ahead of a low pressure system. This system will will bring disturbed weather with possible thunderstorms on Friday. Winds will increase to a strong NW breeze this weekend as subtropical high pressure builds over the Eastern Pacific.
Ca, None. PZ, Small Craft Advisory until 3 AM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm.
