textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1222 PM PDT Sun Aug 16 2026

- Shallower marine layer expected the next few days

- Minor fluctuations in temperatures this week.

SHORT TERM

Issued at 130 PM PDT Sun Aug 16 2026 (This evening through Monday night)

Water vapor imagery continues to show an upper level trough of low pressure off the California Coast and high pressure over the Desert Southwest this afternoon. As a result, California remains situated between the two, with southwesterly flow aloft. There is quite a bit of upper level moisture over the ocean moving through this flow, so expect an increase in high clouds across the region over the next 24 to 36 hours. Meanwhile, we still have a relatively deep mariner layer lingering along the immediate coast. As a result, coastal areas are still running 2 to 3 degrees behind temperatures at this point yesterday, but inland areas are running slightly warmer, given the earlier clearing time. Either way, most locations across our region are still going to be below normal or right at normal for this time of year.

The 12z morning KOAK sounding showed the marine layer around 1800 feet deep, and given the observations this afternoon, doubt it has compressed much if any today. Therefore, expect another good push of low clouds and fog inland this evening and tonight, with similar clear times and temperatures for tomorrow. Palmer

LONG TERM

Issued at 130 PM PDT Sun Aug 16 2026 (Tuesday through next Saturday)

The main story for this week will be the battle between the trough off our coast and the ridge to the southwest, and which one will influence our forecast the most. At this point in time, the models are suggesting that the ridge should be the dominate feature for the first part of the work week, with 850 mb temperatures climbing approximately a degree or so each day through Wednesday, before the influence of the trough takes back over for the latter part of the work week and the weekend as it is forecast to move closer to the coast.

However, this is where things get interesting. There is a lot of upper level moisture filtering northeastward in the southwesterly flow aloft. We are already seeing some thin high clouds associated with the leading edge of that moisture, but there is a large bulk of that moisture (cloud cover) that is not translucent. Therefore, even through the models are suggesting a gradual warm up across the inland areas, current thinking is that this upper level cloud cover will likely limit day time heating and provide a decent insulting blanket at night. And all of this said is not taking the marine layer influence into account. Therefore, my confidence in an actual "warm up" is not high. In fact, my gut says it may likely be dependent on the day, and how much sun we actually see. Therefore, expect most places to remain at or below normal for the next week, with only minor day to day fluctuations possible this week and through next weekend.

Now, you may have also noted that I said this a lot of this moisture is not translucent. In fact, current clean IR band shows what is likely a convective band just south of 25 North and 130 West, so the question is will this moisture get pulled into the flow for us? Maybe, but it does not look likely. There is some hinting at higher precipitable water values upwards of an 1 inch for Thursday and Friday, but any instability with it diminishes as it gets here. Therefore, expect our predominately dry conditions to continue across the region. Palmer

AVIATION

(18Z TAFS) Issued at 1044 AM PDT Sun Aug 16 2026

Stratus, fog, patchy drizzle /MVFR-IFR-LIFR/ are steadily mixing out and dissipating otherwise it's VFR. Stratus, fog and patchy drizzle /MVFR-IFR-LIFR/ redevelop tonight and Monday morning.

Vicinity of SFO...Stratus /MVFR/ mixing out to VFR 1930z today. Stratus /MVFR-IFR/ redevelops tonight and Monday morning. Low clouds /MVFR/ mixing out to VFR 20z Monday. West to northwest wind 5 to 15 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus /IFR/ improving to MVFR-VFR in the afternoon. Stratus /IFR/ redevelops tonight and Monday morning. West to northwest winds 5 to 15 knots.

MARINE

(Today through Friday) Issued at 850 AM PDT Sun Aug 16 2026

A gentle to moderate northwesterly breeze persists into Monday with localized fresh gusts possible across the interior waters. Winds increase to fresh to strong late Monday and remain elevated through the end of the forecast period. Seas of around 4 to 5 feet will build to 7 to 8 feet by mid week. A long period southerly swell around 15 to 17 seconds will continue to diminish through the early work week.

FIRE WEATHER

Issued at 130 PM PDT Sun Aug 16 2026

Expect some nocturnal drying the next few nights as the marine layer gradually compresses. Therefore, expect more widespread fair to moderate recoveries developing over the high elevations, especially in and around the Timber Fire.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.