textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 428 PM PDT Mon Aug 17 2026

- Slight warming trend through Wednesday

- Marine layer remains compressed through mid week

SHORT TERM

Issued at 200 PM PDT Mon Aug 17 2026 (This evening through Tuesday night)

Water vapor imagery continues to show an elongated upper level trough off the West Coast this afternoon, with the parent low centered near 32.5 North and 137.5 West. There are several disturbances moving around this trough, including the one lifting across southwest Oregon that brought all of the high cloud cover to Central and Northern California today. Water vapor imagery also shows high pressure over the Desert Southwest, with California remaining between the two large scale features, with relatively moist southwesterly flow aloft over us. Unfortunately, all of moisture is in the upper atmosphere in the form of high clouds. There has been enough breaks in these clouds though that our daytime temperatures today are warming more than I initially gave them credit for. In fact, most locations are running 3 to 6 degrees warmer today over yesterday. That is in part to the warmer start to the day, but also the combination of increasing 850 mb temperatures, a compressing marine layer, and then sunshine. The question now is whether or not there will be enough clouds to be another insulating blanket tonight? Looking at the IR imagery, think this is a plausible solution, and expect mild conditions once again tonight. The marine layer will return again tonight, but should be shallower (around 1500 feet), and not be quite as widespread as this morning.

The upper level ridge, despite being dirty, will be the dominate weather feature for Tuesday and Tuesday night, helping to continue to minor warming trend, especially across the inland areas. Despite the minor warming trend, daytime temperatures will remain near to below normal through for most areas, with just the far inland areas being above normal. The marine layer will also start to compress, with more patchy fog possible during the late night and early morning hours. Palmer

LONG TERM

Issued at 200 PM PDT Mon Aug 17 2026 (Wednesday through next Sunday)

This upper level ridge will remain our more dominate weather feature at least Wednesday and potentially now into Thursday. Therefore, expect inland areas to potentially see another degree or two of warming on Wednesday, with little change for Thursday, while coastal areas only see minor fluctuations, as a shallow marine layer lingers along the coast.

The upper level low currently near 32.5 North and 137.5 West will finally lift for Friday before moving into the Pacific Northwest for the weekend. This will once again bring a deeper marine layer, stronger onshore winds, and cooler conditions to the Bay Area and Central Coast once again. That being said, the parent trough will remain off the California Coast as another upper level low replaces this first one. While the details are still not entire clear on where this secondary parent low will set up, it will keep California with south or southwesterly flow aloft through the first part of next week. The East Pacific also looks to get active with a series of easterly waves during this time. This could make things a little more interesting around here, should something try to form and slip north around the edge of the ridge. At this point in time, that does not look likely, but can't fully rule it out either. Needless to say, this is something that will bears watching. For now though, expect continued dry through the period. Palmer

AVIATION

(00Z TAFS) Issued at 428 PM PDT Mon Aug 17 2026

Patchy MVFR-IFR stratus lingers at the immediate coast with the rest of the region reporting VFR conditions with high clouds. Moderate onshore pattern breezes will persist into the afternoon and evening hours. This evening and overnight, generally IFR-LIFR stratus is expected to make its way inland and impact most terminals, with patchy fog possible and a low to moderate confidence of impacts to LVK. Stratus will mix out Tuesday morning with gentle to moderate onshore breezes resuming in the afternoon.

Vicinity of SFO... VFR with high clouds and moderate northwest breezes persist through the evening hours. Winds will diminish late in the evening with MVFR-IFR stratus developing overnight, mixing out on Tuesday morning with breezy northwest winds resuming in the afternoon. Low confidence for stratus development late Tuesday evening before the end of the TAF period, which doesn't improve much after the end of the TAF period as the terminal area sits at the edge of where high resolution model output paints the stratus deck.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR conditions will make way to returning IFR-LIFR stratus through the next couple of hours. LIFR conditions will develop overnight with mixing out expected through Tuesday morning, with some uncertainty on clearing times. Moderate confidence that MRY will scatter out sometime Tuesday afternoon. Moderate northwest to west winds will continue through the evening hours, turning light overnight before resuming Tuesday afternoon.

MARINE

(Tonight through next Saturday) Issued at 428 PM PDT Mon Aug 17 2026

Northwesterly winds gradually increase with a fresh to strong breeze developing by late tonight and continuing through the end of the forecast period. Locally stronger winds are possible in the coastal jet regions north of Point Reyes and along the Big Sur coast. Seas build to 7 to 9 feet by Tuesday and Wednesday before subsiding late week.

FIRE WEATHER

Issued at 200 PM PDT Mon Aug 17 2026

The marine layer will gradually compress over the next 24 to 36 hours, as high pressure builds over the region. As a result, nocturnal drying will be possible through at least mid-week for the higher elevations, with more widespread fair to moderate recoveries developing over the higher elevations, especially in and around the Timber Fire.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 3 AM Tuesday to 3 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.